xref: /external/chromium_org/chrome/browser/ui/tabs/tab_strip_model.cc

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "chrome/browser/ui/tabs/tab_strip_model.h"

#include <algorithm>
#include <map>
#include <string>

#include "base/metrics/histogram.h"
#include "base/stl_util.h"
#include "chrome/app/chrome_command_ids.h"
#include "chrome/browser/browser_shutdown.h"
#include "chrome/browser/defaults.h"
#include "chrome/browser/extensions/tab_helper.h"
#include "chrome/browser/profiles/profile.h"
#include "chrome/browser/ui/tab_contents/core_tab_helper.h"
#include "chrome/browser/ui/tab_contents/core_tab_helper_delegate.h"
#include "chrome/browser/ui/tabs/tab_strip_model_delegate.h"
#include "chrome/browser/ui/tabs/tab_strip_model_order_controller.h"
#include "chrome/browser/ui/tabs/tab_utils.h"
#include "chrome/browser/ui/web_contents_sizer.h"
#include "chrome/common/url_constants.h"
#include "components/web_modal/popup_manager.h"
#include "content/public/browser/render_process_host.h"
#include "content/public/browser/user_metrics.h"
#include "content/public/browser/web_contents.h"
#include "content/public/browser/web_contents_observer.h"
using base::UserMetricsAction;
using content::WebContents;

namespace {

// Returns true if the specified transition is one of the types that cause the
// opener relationships for the tab in which the transition occurred to be
// forgotten. This is generally any navigation that isn't a link click (i.e.
// any navigation that can be considered to be the start of a new task distinct
// from what had previously occurred in that tab).
bool ShouldForgetOpenersForTransition(ui::PageTransition transition) {
  return transition == ui::PAGE_TRANSITION_TYPED ||
      transition == ui::PAGE_TRANSITION_AUTO_BOOKMARK ||
      transition == ui::PAGE_TRANSITION_GENERATED ||
      transition == ui::PAGE_TRANSITION_KEYWORD ||
      transition == ui::PAGE_TRANSITION_AUTO_TOPLEVEL;
}

// CloseTracker is used when closing a set of WebContents. It listens for
// deletions of the WebContents and removes from the internal set any time one
// is deleted.
class CloseTracker {
 public:
  typedef std::vector<WebContents*> Contents;

  explicit CloseTracker(const Contents& contents);
  virtual ~CloseTracker();

  // Returns true if there is another WebContents in the Tracker.
  bool HasNext() const;

  // Returns the next WebContents, or NULL if there are no more.
  WebContents* Next();

 private:
  class DeletionObserver : public content::WebContentsObserver {
   public:
    DeletionObserver(CloseTracker* parent, WebContents* web_contents)
        : WebContentsObserver(web_contents),
          parent_(parent) {
    }

   private:
    // WebContentsObserver:
    virtual void WebContentsDestroyed() OVERRIDE {
      parent_->OnWebContentsDestroyed(this);
    }

    CloseTracker* parent_;

    DISALLOW_COPY_AND_ASSIGN(DeletionObserver);
  };

  void OnWebContentsDestroyed(DeletionObserver* observer);

  typedef std::vector<DeletionObserver*> Observers;
  Observers observers_;

  DISALLOW_COPY_AND_ASSIGN(CloseTracker);
};

CloseTracker::CloseTracker(const Contents& contents) {
  for (size_t i = 0; i < contents.size(); ++i)
    observers_.push_back(new DeletionObserver(this, contents[i]));
}

CloseTracker::~CloseTracker() {
  DCHECK(observers_.empty());
}

bool CloseTracker::HasNext() const {
  return !observers_.empty();
}

WebContents* CloseTracker::Next() {
  if (observers_.empty())
    return NULL;

  DeletionObserver* observer = observers_[0];
  WebContents* web_contents = observer->web_contents();
  observers_.erase(observers_.begin());
  delete observer;
  return web_contents;
}

void CloseTracker::OnWebContentsDestroyed(DeletionObserver* observer) {
  Observers::iterator i =
      std::find(observers_.begin(), observers_.end(), observer);
  if (i != observers_.end()) {
    delete *i;
    observers_.erase(i);
    return;
  }
  NOTREACHED() << "WebContents destroyed that wasn't in the list";
}

}  // namespace

///////////////////////////////////////////////////////////////////////////////
// WebContentsData

// An object to hold a reference to a WebContents that is in a tabstrip, as
// well as other various properties it has.
class TabStripModel::WebContentsData : public content::WebContentsObserver {
 public:
  WebContentsData(TabStripModel* tab_strip_model, WebContents* a_contents);

  // Changes the WebContents that this WebContentsData tracks.
  void SetWebContents(WebContents* contents);
  WebContents* web_contents() { return contents_; }

  // Create a relationship between this WebContentsData and other
  // WebContentses. Used to identify which WebContents to select next after
  // one is closed.
  WebContents* group() const { return group_; }
  void set_group(WebContents* value) { group_ = value; }
  WebContents* opener() const { return opener_; }
  void set_opener(WebContents* value) { opener_ = value; }

  // Alters the properties of the WebContents.
  bool reset_group_on_select() const { return reset_group_on_select_; }
  void set_reset_group_on_select(bool value) { reset_group_on_select_ = value; }
  bool pinned() const { return pinned_; }
  void set_pinned(bool value) { pinned_ = value; }
  bool blocked() const { return blocked_; }
  void set_blocked(bool value) { blocked_ = value; }
  bool discarded() const { return discarded_; }
  void set_discarded(bool value) { discarded_ = value; }

 private:
  // Make sure that if someone deletes this WebContents out from under us, it
  // is properly removed from the tab strip.
  virtual void WebContentsDestroyed() OVERRIDE;

  // The WebContents being tracked by this WebContentsData. The
  // WebContentsObserver does keep a reference, but when the WebContents is
  // deleted, the WebContentsObserver reference is NULLed and thus inaccessible.
  WebContents* contents_;

  // The TabStripModel containing this WebContents.
  TabStripModel* tab_strip_model_;

  // The group is used to model a set of tabs spawned from a single parent
  // tab. This value is preserved for a given tab as long as the tab remains
  // navigated to the link it was initially opened at or some navigation from
  // that page (i.e. if the user types or visits a bookmark or some other
  // navigation within that tab, the group relationship is lost). This
  // property can safely be used to implement features that depend on a
  // logical group of related tabs.
  WebContents* group_;

  // The owner models the same relationship as group, except it is more
  // easily discarded, e.g. when the user switches to a tab not part of the
  // same group. This property is used to determine what tab to select next
  // when one is closed.
  WebContents* opener_;

  // True if our group should be reset the moment selection moves away from
  // this tab. This is the case for tabs opened in the foreground at the end
  // of the TabStrip while viewing another Tab. If these tabs are closed
  // before selection moves elsewhere, their opener is selected. But if
  // selection shifts to _any_ tab (including their opener), the group
  // relationship is reset to avoid confusing close sequencing.
  bool reset_group_on_select_;

  // Is the tab pinned?
  bool pinned_;

  // Is the tab interaction blocked by a modal dialog?
  bool blocked_;

  // Has the tab data been discarded to save memory?
  bool discarded_;

  DISALLOW_COPY_AND_ASSIGN(WebContentsData);
};

TabStripModel::WebContentsData::WebContentsData(TabStripModel* tab_strip_model,
                                                WebContents* contents)
    : content::WebContentsObserver(contents),
      contents_(contents),
      tab_strip_model_(tab_strip_model),
      group_(NULL),
      opener_(NULL),
      reset_group_on_select_(false),
      pinned_(false),
      blocked_(false),
      discarded_(false) {
}

void TabStripModel::WebContentsData::SetWebContents(WebContents* contents) {
  contents_ = contents;
  Observe(contents);
}

void TabStripModel::WebContentsData::WebContentsDestroyed() {
  DCHECK_EQ(contents_, web_contents());

  // Note that we only detach the contents here, not close it - it's
  // already been closed. We just want to undo our bookkeeping.
  int index = tab_strip_model_->GetIndexOfWebContents(web_contents());
  DCHECK_NE(TabStripModel::kNoTab, index);
  tab_strip_model_->DetachWebContentsAt(index);
}

///////////////////////////////////////////////////////////////////////////////
// TabStripModel, public:

TabStripModel::TabStripModel(TabStripModelDelegate* delegate, Profile* profile)
    : delegate_(delegate),
      profile_(profile),
      closing_all_(false),
      in_notify_(false),
      weak_factory_(this) {
  DCHECK(delegate_);
  order_controller_.reset(new TabStripModelOrderController(this));
}

TabStripModel::~TabStripModel() {
  FOR_EACH_OBSERVER(TabStripModelObserver, observers_,
                    TabStripModelDeleted());
  STLDeleteElements(&contents_data_);
  order_controller_.reset();
}

void TabStripModel::AddObserver(TabStripModelObserver* observer) {
  observers_.AddObserver(observer);
}

void TabStripModel::RemoveObserver(TabStripModelObserver* observer) {
  observers_.RemoveObserver(observer);
}

bool TabStripModel::ContainsIndex(int index) const {
  return index >= 0 && index < count();
}

void TabStripModel::AppendWebContents(WebContents* contents,
                                      bool foreground) {
  InsertWebContentsAt(count(), contents,
                      foreground ? (ADD_INHERIT_GROUP | ADD_ACTIVE) :
                                   ADD_NONE);
}

void TabStripModel::InsertWebContentsAt(int index,
                                        WebContents* contents,
                                        int add_types) {
  delegate_->WillAddWebContents(contents);

  bool active = add_types & ADD_ACTIVE;
  // Force app tabs to be pinned.
  extensions::TabHelper* extensions_tab_helper =
      extensions::TabHelper::FromWebContents(contents);
  bool pin = extensions_tab_helper->is_app() || add_types & ADD_PINNED;
  index = ConstrainInsertionIndex(index, pin);

  // In tab dragging situations, if the last tab in the window was detached
  // then the user aborted the drag, we will have the |closing_all_| member
  // set (see DetachWebContentsAt) which will mess with our mojo here. We need
  // to clear this bit.
  closing_all_ = false;

  // Have to get the active contents before we monkey with the contents
  // otherwise we run into problems when we try to change the active contents
  // since the old contents and the new contents will be the same...
  WebContents* active_contents = GetActiveWebContents();
  WebContentsData* data = new WebContentsData(this, contents);
  data->set_pinned(pin);
  if ((add_types & ADD_INHERIT_GROUP) && active_contents) {
    if (active) {
      // Forget any existing relationships, we don't want to make things too
      // confusing by having multiple groups active at the same time.
      ForgetAllOpeners();
    }
    // Anything opened by a link we deem to have an opener.
    data->set_group(active_contents);
    data->set_opener(active_contents);
  } else if ((add_types & ADD_INHERIT_OPENER) && active_contents) {
    if (active) {
      // Forget any existing relationships, we don't want to make things too
      // confusing by having multiple groups active at the same time.
      ForgetAllOpeners();
    }
    data->set_opener(active_contents);
  }

  // TODO(gbillock): Ask the bubble manager whether the WebContents should be
  // blocked, or just let the bubble manager make the blocking call directly
  // and not use this at all.
  web_modal::PopupManager* popup_manager =
      web_modal::PopupManager::FromWebContents(contents);
  if (popup_manager)
    data->set_blocked(popup_manager->IsWebModalDialogActive(contents));

  contents_data_.insert(contents_data_.begin() + index, data);

  selection_model_.IncrementFrom(index);

  FOR_EACH_OBSERVER(TabStripModelObserver, observers_,
                    TabInsertedAt(contents, index, active));
  if (active) {
    ui::ListSelectionModel new_model;
    new_model.Copy(selection_model_);
    new_model.SetSelectedIndex(index);
    SetSelection(new_model, NOTIFY_DEFAULT);
  }
}

WebContents* TabStripModel::ReplaceWebContentsAt(int index,
                                                 WebContents* new_contents) {
  delegate_->WillAddWebContents(new_contents);

  DCHECK(ContainsIndex(index));
  WebContents* old_contents = GetWebContentsAtImpl(index);

  ForgetOpenersAndGroupsReferencing(old_contents);

  contents_data_[index]->SetWebContents(new_contents);

  FOR_EACH_OBSERVER(TabStripModelObserver, observers_,
                    TabReplacedAt(this, old_contents, new_contents, index));

  // When the active WebContents is replaced send out a selection notification
  // too. We do this as nearly all observers need to treat a replacement of the
  // selected contents as the selection changing.
  if (active_index() == index) {
    FOR_EACH_OBSERVER(
        TabStripModelObserver,
        observers_,
        ActiveTabChanged(old_contents,
                         new_contents,
                         active_index(),
                         TabStripModelObserver::CHANGE_REASON_REPLACED));
  }
  return old_contents;
}

WebContents* TabStripModel::DiscardWebContentsAt(int index) {
  DCHECK(ContainsIndex(index));
  // Do not discard active tab.
  if (active_index() == index)
    return NULL;

  WebContents* null_contents =
      WebContents::Create(WebContents::CreateParams(profile()));
  WebContents* old_contents = GetWebContentsAtImpl(index);
  // Copy over the state from the navigation controller so we preserve the
  // back/forward history and continue to display the correct title/favicon.
  null_contents->GetController().CopyStateFrom(old_contents->GetController());
  // Replace the tab we're discarding with the null version.
  ReplaceWebContentsAt(index, null_contents);
  // Mark the tab so it will reload when we click.
  contents_data_[index]->set_discarded(true);
  // Discard the old tab's renderer.
  // TODO(jamescook): This breaks script connections with other tabs.
  // We need to find a different approach that doesn't do that, perhaps based
  // on navigation to swappedout://.
  delete old_contents;
  return null_contents;
}

WebContents* TabStripModel::DetachWebContentsAt(int index) {
  CHECK(!in_notify_);
  if (contents_data_.empty())
    return NULL;

  DCHECK(ContainsIndex(index));

  WebContents* removed_contents = GetWebContentsAtImpl(index);
  bool was_selected = IsTabSelected(index);
  int next_selected_index = order_controller_->DetermineNewSelectedIndex(index);
  delete contents_data_[index];
  contents_data_.erase(contents_data_.begin() + index);
  ForgetOpenersAndGroupsReferencing(removed_contents);
  if (empty())
    closing_all_ = true;
  FOR_EACH_OBSERVER(TabStripModelObserver, observers_,
                    TabDetachedAt(removed_contents, index));
  if (empty()) {
    selection_model_.Clear();
    // TabDetachedAt() might unregister observers, so send |TabStripEmpty()| in
    // a second pass.
    FOR_EACH_OBSERVER(TabStripModelObserver, observers_, TabStripEmpty());
  } else {
    int old_active = active_index();
    selection_model_.DecrementFrom(index);
    ui::ListSelectionModel old_model;
    old_model.Copy(selection_model_);
    if (index == old_active) {
      NotifyIfTabDeactivated(removed_contents);
      if (!selection_model_.empty()) {
        // The active tab was removed, but there is still something selected.
        // Move the active and anchor to the first selected index.
        selection_model_.set_active(selection_model_.selected_indices()[0]);
        selection_model_.set_anchor(selection_model_.active());
      } else {
        // The active tab was removed and nothing is selected. Reset the
        // selection and send out notification.
        selection_model_.SetSelectedIndex(next_selected_index);
      }
      NotifyIfActiveTabChanged(removed_contents, NOTIFY_DEFAULT);
    }

    // Sending notification in case the detached tab was selected. Using
    // NotifyIfActiveOrSelectionChanged() here would not guarantee that a
    // notification is sent even though the tab selection has changed because
    // |old_model| is stored after calling DecrementFrom().
    if (was_selected) {
      FOR_EACH_OBSERVER(TabStripModelObserver, observers_,
                        TabSelectionChanged(this, old_model));
    }
  }
  return removed_contents;
}

void TabStripModel::ActivateTabAt(int index, bool user_gesture) {
  DCHECK(ContainsIndex(index));
  ui::ListSelectionModel new_model;
  new_model.Copy(selection_model_);
  new_model.SetSelectedIndex(index);
  SetSelection(new_model, user_gesture ? NOTIFY_USER_GESTURE : NOTIFY_DEFAULT);
}

void TabStripModel::AddTabAtToSelection(int index) {
  DCHECK(ContainsIndex(index));
  ui::ListSelectionModel new_model;
  new_model.Copy(selection_model_);
  new_model.AddIndexToSelection(index);
  SetSelection(new_model, NOTIFY_DEFAULT);
}

void TabStripModel::MoveWebContentsAt(int index,
                                      int to_position,
                                      bool select_after_move) {
  DCHECK(ContainsIndex(index));
  if (index == to_position)
    return;

  int first_non_mini_tab = IndexOfFirstNonMiniTab();
  if ((index < first_non_mini_tab && to_position >= first_non_mini_tab) ||
      (to_position < first_non_mini_tab && index >= first_non_mini_tab)) {
    // This would result in mini tabs mixed with non-mini tabs. We don't allow
    // that.
    return;
  }

  MoveWebContentsAtImpl(index, to_position, select_after_move);
}

void TabStripModel::MoveSelectedTabsTo(int index) {
  int total_mini_count = IndexOfFirstNonMiniTab();
  int selected_mini_count = 0;
  int selected_count =
      static_cast<int>(selection_model_.selected_indices().size());
  for (int i = 0; i < selected_count &&
           IsMiniTab(selection_model_.selected_indices()[i]); ++i) {
    selected_mini_count++;
  }

  // To maintain that all mini-tabs occur before non-mini-tabs we move them
  // first.
  if (selected_mini_count > 0) {
    MoveSelectedTabsToImpl(
        std::min(total_mini_count - selected_mini_count, index), 0u,
        selected_mini_count);
    if (index > total_mini_count - selected_mini_count) {
      // We're being told to drag mini-tabs to an invalid location. Adjust the
      // index such that non-mini-tabs end up at a location as though we could
      // move the mini-tabs to index. See description in header for more
      // details.
      index += selected_mini_count;
    }
  }
  if (selected_mini_count == selected_count)
    return;

  // Then move the non-pinned tabs.
  MoveSelectedTabsToImpl(std::max(index, total_mini_count),
                         selected_mini_count,
                         selected_count - selected_mini_count);
}

WebContents* TabStripModel::GetActiveWebContents() const {
  return GetWebContentsAt(active_index());
}

WebContents* TabStripModel::GetWebContentsAt(int index) const {
  if (ContainsIndex(index))
    return GetWebContentsAtImpl(index);
  return NULL;
}

int TabStripModel::GetIndexOfWebContents(const WebContents* contents) const {
  for (size_t i = 0; i < contents_data_.size(); ++i) {
    if (contents_data_[i]->web_contents() == contents)
      return i;
  }
  return kNoTab;
}

void TabStripModel::UpdateWebContentsStateAt(int index,
    TabStripModelObserver::TabChangeType change_type) {
  DCHECK(ContainsIndex(index));

  FOR_EACH_OBSERVER(TabStripModelObserver, observers_,
      TabChangedAt(GetWebContentsAtImpl(index), index, change_type));
}

void TabStripModel::CloseAllTabs() {
  // Set state so that observers can adjust their behavior to suit this
  // specific condition when CloseWebContentsAt causes a flurry of
  // Close/Detach/Select notifications to be sent.
  closing_all_ = true;
  std::vector<int> closing_tabs;
  for (int i = count() - 1; i >= 0; --i)
    closing_tabs.push_back(i);
  InternalCloseTabs(closing_tabs, CLOSE_CREATE_HISTORICAL_TAB);
}

bool TabStripModel::CloseWebContentsAt(int index, uint32 close_types) {
  DCHECK(ContainsIndex(index));
  std::vector<int> closing_tabs;
  closing_tabs.push_back(index);
  return InternalCloseTabs(closing_tabs, close_types);
}

bool TabStripModel::TabsAreLoading() const {
  for (WebContentsDataVector::const_iterator iter = contents_data_.begin();
       iter != contents_data_.end(); ++iter) {
    if ((*iter)->web_contents()->IsLoading())
      return true;
  }
  return false;
}

WebContents* TabStripModel::GetOpenerOfWebContentsAt(int index) {
  DCHECK(ContainsIndex(index));
  return contents_data_[index]->opener();
}

void TabStripModel::SetOpenerOfWebContentsAt(int index,
                                             WebContents* opener) {
  DCHECK(ContainsIndex(index));
  DCHECK(opener);
  contents_data_[index]->set_opener(opener);
}

int TabStripModel::GetIndexOfNextWebContentsOpenedBy(const WebContents* opener,
                                                     int start_index,
                                                     bool use_group) const {
  DCHECK(opener);
  DCHECK(ContainsIndex(start_index));

  // Check tabs after start_index first.
  for (int i = start_index + 1; i < count(); ++i) {
    if (OpenerMatches(contents_data_[i], opener, use_group))
      return i;
  }
  // Then check tabs before start_index, iterating backwards.
  for (int i = start_index - 1; i >= 0; --i) {
    if (OpenerMatches(contents_data_[i], opener, use_group))
      return i;
  }
  return kNoTab;
}

int TabStripModel::GetIndexOfLastWebContentsOpenedBy(const WebContents* opener,
                                                     int start_index) const {
  DCHECK(opener);
  DCHECK(ContainsIndex(start_index));

  for (int i = contents_data_.size() - 1; i > start_index; --i) {
    if (contents_data_[i]->opener() == opener)
      return i;
  }
  return kNoTab;
}

void TabStripModel::TabNavigating(WebContents* contents,
                                  ui::PageTransition transition) {
  if (ShouldForgetOpenersForTransition(transition)) {
    // Don't forget the openers if this tab is a New Tab page opened at the
    // end of the TabStrip (e.g. by pressing Ctrl+T). Give the user one
    // navigation of one of these transition types before resetting the
    // opener relationships (this allows for the use case of opening a new
    // tab to do a quick look-up of something while viewing a tab earlier in
    // the strip). We can make this heuristic more permissive if need be.
    if (!IsNewTabAtEndOfTabStrip(contents)) {
      // If the user navigates the current tab to another page in any way
      // other than by clicking a link, we want to pro-actively forget all
      // TabStrip opener relationships since we assume they're beginning a
      // different task by reusing the current tab.
      ForgetAllOpeners();
      // In this specific case we also want to reset the group relationship,
      // since it is now technically invalid.
      ForgetGroup(contents);
    }
  }
}

void TabStripModel::ForgetAllOpeners() {
  // Forget all opener memories so we don't do anything weird with tab
  // re-selection ordering.
  for (WebContentsDataVector::const_iterator iter = contents_data_.begin();
       iter != contents_data_.end(); ++iter)
    (*iter)->set_opener(NULL);
}

void TabStripModel::ForgetGroup(WebContents* contents) {
  int index = GetIndexOfWebContents(contents);
  DCHECK(ContainsIndex(index));
  contents_data_[index]->set_group(NULL);
  contents_data_[index]->set_opener(NULL);
}

bool TabStripModel::ShouldResetGroupOnSelect(WebContents* contents) const {
  int index = GetIndexOfWebContents(contents);
  DCHECK(ContainsIndex(index));
  return contents_data_[index]->reset_group_on_select();
}

void TabStripModel::SetTabBlocked(int index, bool blocked) {
  DCHECK(ContainsIndex(index));
  if (contents_data_[index]->blocked() == blocked)
    return;
  contents_data_[index]->set_blocked(blocked);
  FOR_EACH_OBSERVER(
      TabStripModelObserver, observers_,
      TabBlockedStateChanged(contents_data_[index]->web_contents(),
                             index));
}

void TabStripModel::SetTabPinned(int index, bool pinned) {
  DCHECK(ContainsIndex(index));
  if (contents_data_[index]->pinned() == pinned)
    return;

  if (IsAppTab(index)) {
    if (!pinned) {
      // App tabs should always be pinned.
      NOTREACHED();
      return;
    }
    // Changing the pinned state of an app tab doesn't affect its mini-tab
    // status.
    contents_data_[index]->set_pinned(pinned);
  } else {
    // The tab is not an app tab, its position may have to change as the
    // mini-tab state is changing.
    int non_mini_tab_index = IndexOfFirstNonMiniTab();
    contents_data_[index]->set_pinned(pinned);
    if (pinned && index != non_mini_tab_index) {
      MoveWebContentsAtImpl(index, non_mini_tab_index, false);
      index = non_mini_tab_index;
    } else if (!pinned && index + 1 != non_mini_tab_index) {
      MoveWebContentsAtImpl(index, non_mini_tab_index - 1, false);
      index = non_mini_tab_index - 1;
    }

    FOR_EACH_OBSERVER(TabStripModelObserver, observers_,
                      TabMiniStateChanged(contents_data_[index]->web_contents(),
                                          index));
  }

  // else: the tab was at the boundary and its position doesn't need to change.
  FOR_EACH_OBSERVER(TabStripModelObserver, observers_,
                    TabPinnedStateChanged(contents_data_[index]->web_contents(),
                                          index));
}

bool TabStripModel::IsTabPinned(int index) const {
  DCHECK(ContainsIndex(index));
  return contents_data_[index]->pinned();
}

bool TabStripModel::IsMiniTab(int index) const {
  return IsTabPinned(index) || IsAppTab(index);
}

bool TabStripModel::IsAppTab(int index) const {
  WebContents* contents = GetWebContentsAt(index);
  return contents && extensions::TabHelper::FromWebContents(contents)->is_app();
}

bool TabStripModel::IsTabBlocked(int index) const {
  return contents_data_[index]->blocked();
}

bool TabStripModel::IsTabDiscarded(int index) const {
  return contents_data_[index]->discarded();
}

int TabStripModel::IndexOfFirstNonMiniTab() const {
  for (size_t i = 0; i < contents_data_.size(); ++i) {
    if (!IsMiniTab(static_cast<int>(i)))
      return static_cast<int>(i);
  }
  // No mini-tabs.
  return count();
}

int TabStripModel::ConstrainInsertionIndex(int index, bool mini_tab) {
  return mini_tab ? std::min(std::max(0, index), IndexOfFirstNonMiniTab()) :
      std::min(count(), std::max(index, IndexOfFirstNonMiniTab()));
}

void TabStripModel::ExtendSelectionTo(int index) {
  DCHECK(ContainsIndex(index));
  ui::ListSelectionModel new_model;
  new_model.Copy(selection_model_);
  new_model.SetSelectionFromAnchorTo(index);
  SetSelection(new_model, NOTIFY_DEFAULT);
}

void TabStripModel::ToggleSelectionAt(int index) {
  DCHECK(ContainsIndex(index));
  ui::ListSelectionModel new_model;
  new_model.Copy(selection_model());
  if (selection_model_.IsSelected(index)) {
    if (selection_model_.size() == 1) {
      // One tab must be selected and this tab is currently selected so we can't
      // unselect it.
      return;
    }
    new_model.RemoveIndexFromSelection(index);
    new_model.set_anchor(index);
    if (new_model.active() == index ||
        new_model.active() == ui::ListSelectionModel::kUnselectedIndex)
      new_model.set_active(new_model.selected_indices()[0]);
  } else {
    new_model.AddIndexToSelection(index);
    new_model.set_anchor(index);
    new_model.set_active(index);
  }
  SetSelection(new_model, NOTIFY_DEFAULT);
}

void TabStripModel::AddSelectionFromAnchorTo(int index) {
  ui::ListSelectionModel new_model;
  new_model.Copy(selection_model_);
  new_model.AddSelectionFromAnchorTo(index);
  SetSelection(new_model, NOTIFY_DEFAULT);
}

bool TabStripModel::IsTabSelected(int index) const {
  DCHECK(ContainsIndex(index));
  return selection_model_.IsSelected(index);
}

void TabStripModel::SetSelectionFromModel(
    const ui::ListSelectionModel& source) {
  DCHECK_NE(ui::ListSelectionModel::kUnselectedIndex, source.active());
  SetSelection(source, NOTIFY_DEFAULT);
}

void TabStripModel::AddWebContents(WebContents* contents,
                                   int index,
                                   ui::PageTransition transition,
                                   int add_types) {
  // If the newly-opened tab is part of the same task as the parent tab, we want
  // to inherit the parent's "group" attribute, so that if this tab is then
  // closed we'll jump back to the parent tab.
  bool inherit_group = (add_types & ADD_INHERIT_GROUP) == ADD_INHERIT_GROUP;

  if (transition == ui::PAGE_TRANSITION_LINK &&
      (add_types & ADD_FORCE_INDEX) == 0) {
    // We assume tabs opened via link clicks are part of the same task as their
    // parent.  Note that when |force_index| is true (e.g. when the user
    // drag-and-drops a link to the tab strip), callers aren't really handling
    // link clicks, they just want to score the navigation like a link click in
    // the history backend, so we don't inherit the group in this case.
    index = order_controller_->DetermineInsertionIndex(transition,
                                                       add_types & ADD_ACTIVE);
    inherit_group = true;
  } else {
    // For all other types, respect what was passed to us, normalizing -1s and
    // values that are too large.
    if (index < 0 || index > count())
      index = count();
  }

  if (transition == ui::PAGE_TRANSITION_TYPED && index == count()) {
    // Also, any tab opened at the end of the TabStrip with a "TYPED"
    // transition inherit group as well. This covers the cases where the user
    // creates a New Tab (e.g. Ctrl+T, or clicks the New Tab button), or types
    // in the address bar and presses Alt+Enter. This allows for opening a new
    // Tab to quickly look up something. When this Tab is closed, the old one
    // is re-selected, not the next-adjacent.
    inherit_group = true;
  }
  InsertWebContentsAt(index, contents,
                      add_types | (inherit_group ? ADD_INHERIT_GROUP : 0));
  // Reset the index, just in case insert ended up moving it on us.
  index = GetIndexOfWebContents(contents);

  if (inherit_group && transition == ui::PAGE_TRANSITION_TYPED)
    contents_data_[index]->set_reset_group_on_select(true);

  // TODO(sky): figure out why this is here and not in InsertWebContentsAt. When
  // here we seem to get failures in startup perf tests.
  // Ensure that the new WebContentsView begins at the same size as the
  // previous WebContentsView if it existed.  Otherwise, the initial WebKit
  // layout will be performed based on a width of 0 pixels, causing a
  // very long, narrow, inaccurate layout.  Because some scripts on pages (as
  // well as WebKit's anchor link location calculation) are run on the
  // initial layout and not recalculated later, we need to ensure the first
  // layout is performed with sane view dimensions even when we're opening a
  // new background tab.
  if (WebContents* old_contents = GetActiveWebContents()) {
    if ((add_types & ADD_ACTIVE) == 0) {
      ResizeWebContents(contents, old_contents->GetContainerBounds().size());
    }
  }
}

void TabStripModel::CloseSelectedTabs() {
  InternalCloseTabs(selection_model_.selected_indices(),
                    CLOSE_CREATE_HISTORICAL_TAB | CLOSE_USER_GESTURE);
}

void TabStripModel::SelectNextTab() {
  SelectRelativeTab(true);
}

void TabStripModel::SelectPreviousTab() {
  SelectRelativeTab(false);
}

void TabStripModel::SelectLastTab() {
  ActivateTabAt(count() - 1, true);
}

void TabStripModel::MoveTabNext() {
  // TODO: this likely needs to be updated for multi-selection.
  int new_index = std::min(active_index() + 1, count() - 1);
  MoveWebContentsAt(active_index(), new_index, true);
}

void TabStripModel::MoveTabPrevious() {
  // TODO: this likely needs to be updated for multi-selection.
  int new_index = std::max(active_index() - 1, 0);
  MoveWebContentsAt(active_index(), new_index, true);
}

// Context menu functions.
bool TabStripModel::IsContextMenuCommandEnabled(
    int context_index, ContextMenuCommand command_id) const {
  DCHECK(command_id > CommandFirst && command_id < CommandLast);
  switch (command_id) {
    case CommandNewTab:
    case CommandCloseTab:
      return true;

    case CommandReload: {
      std::vector<int> indices = GetIndicesForCommand(context_index);
      for (size_t i = 0; i < indices.size(); ++i) {
        WebContents* tab = GetWebContentsAt(indices[i]);
        if (tab) {
          CoreTabHelperDelegate* core_delegate =
              CoreTabHelper::FromWebContents(tab)->delegate();
          if (!core_delegate || core_delegate->CanReloadContents(tab))
            return true;
        }
      }
      return false;
    }

    case CommandCloseOtherTabs:
    case CommandCloseTabsToRight:
      return !GetIndicesClosedByCommand(context_index, command_id).empty();

    case CommandDuplicate: {
      std::vector<int> indices = GetIndicesForCommand(context_index);
      for (size_t i = 0; i < indices.size(); ++i) {
        if (delegate_->CanDuplicateContentsAt(indices[i]))
          return true;
      }
      return false;
    }

    case CommandRestoreTab:
      return delegate_->GetRestoreTabType() !=
          TabStripModelDelegate::RESTORE_NONE;

    case CommandTogglePinned: {
      std::vector<int> indices = GetIndicesForCommand(context_index);
      for (size_t i = 0; i < indices.size(); ++i) {
        if (!IsAppTab(indices[i]))
          return true;
      }
      return false;
    }

    case CommandToggleTabAudioMuted: {
      std::vector<int> indices = GetIndicesForCommand(context_index);
      for (size_t i = 0; i < indices.size(); ++i) {
        if (!chrome::CanToggleAudioMute(GetWebContentsAt(indices[i])))
          return false;
      }
      return true;
    }

    case CommandBookmarkAllTabs:
      return browser_defaults::bookmarks_enabled &&
          delegate_->CanBookmarkAllTabs();

    case CommandSelectByDomain:
    case CommandSelectByOpener:
      return true;

    default:
      NOTREACHED();
  }
  return false;
}

void TabStripModel::ExecuteContextMenuCommand(
    int context_index, ContextMenuCommand command_id) {
  DCHECK(command_id > CommandFirst && command_id < CommandLast);
  switch (command_id) {
    case CommandNewTab:
      content::RecordAction(UserMetricsAction("TabContextMenu_NewTab"));
      UMA_HISTOGRAM_ENUMERATION("Tab.NewTab",
                                TabStripModel::NEW_TAB_CONTEXT_MENU,
                                TabStripModel::NEW_TAB_ENUM_COUNT);
      delegate()->AddTabAt(GURL(), context_index + 1, true);
      break;

    case CommandReload: {
      content::RecordAction(UserMetricsAction("TabContextMenu_Reload"));
      std::vector<int> indices = GetIndicesForCommand(context_index);
      for (size_t i = 0; i < indices.size(); ++i) {
        WebContents* tab = GetWebContentsAt(indices[i]);
        if (tab) {
          CoreTabHelperDelegate* core_delegate =
              CoreTabHelper::FromWebContents(tab)->delegate();
          if (!core_delegate || core_delegate->CanReloadContents(tab))
            tab->GetController().Reload(true);
        }
      }
      break;
    }

    case CommandDuplicate: {
      content::RecordAction(UserMetricsAction("TabContextMenu_Duplicate"));
      std::vector<int> indices = GetIndicesForCommand(context_index);
      // Copy the WebContents off as the indices will change as tabs are
      // duplicated.
      std::vector<WebContents*> tabs;
      for (size_t i = 0; i < indices.size(); ++i)
        tabs.push_back(GetWebContentsAt(indices[i]));