1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "chrome/renderer/prerender/prerender_helper.h"
6
7#include "base/metrics/field_trial.h"
8#include "base/metrics/histogram.h"
9#include "chrome/common/prerender_messages.h"
10#include "content/public/renderer/document_state.h"
11#include "content/public/renderer/render_frame.h"
12#include "content/public/renderer/render_view.h"
13#include "third_party/WebKit/public/web/WebFrame.h"
14#include "third_party/WebKit/public/web/WebView.h"
15
16using content::DocumentState;
17
18namespace {
19
20// Updates the visibility state of the RenderFrame.  Must be called whenever
21// prerendering starts or finishes and the page is about to be show.  At both
22// those times, the RenderFrame is hidden.
23void UpdateVisibilityState(content::RenderFrame* render_frame) {
24  // TODO(jam): until the prerendering code works on frames instead of views, we
25  // have to do this awkward check.
26  content::RenderView* render_view = render_frame->GetRenderView();
27  if (render_view->GetMainRenderFrame() == render_frame) {
28    render_view->GetWebView()->setVisibilityState(
29        render_view->GetVisibilityState(), false);
30  }
31}
32
33}  // namespace
34
35namespace prerender {
36
37PrerenderHelper::PrerenderHelper(content::RenderFrame* render_frame)
38    : content::RenderFrameObserver(render_frame),
39      content::RenderFrameObserverTracker<PrerenderHelper>(render_frame) {
40  UpdateVisibilityState(render_frame);
41}
42
43PrerenderHelper::~PrerenderHelper() {
44}
45
46// static.
47bool PrerenderHelper::IsPrerendering(const content::RenderFrame* render_frame) {
48  return PrerenderHelper::Get(render_frame) != NULL;
49}
50
51bool PrerenderHelper::OnMessageReceived(
52    const IPC::Message& message) {
53  IPC_BEGIN_MESSAGE_MAP(PrerenderHelper, message)
54    IPC_MESSAGE_HANDLER(PrerenderMsg_SetIsPrerendering, OnSetIsPrerendering)
55  IPC_END_MESSAGE_MAP()
56  // Return false on ViewMsg_SetIsPrerendering so other observers can see the
57  // message.
58  return false;
59}
60
61void PrerenderHelper::OnSetIsPrerendering(bool is_prerendering) {
62  // Immediately after construction, |this| may receive the message that
63  // triggered its creation.  If so, ignore it.
64  if (is_prerendering)
65    return;
66
67  content::RenderFrame* frame = render_frame();
68  // |this| must be deleted so PrerenderHelper::IsPrerendering returns false
69  // when the visibility state is updated, so the visibility state string will
70  // not be "prerendered".
71  delete this;
72
73  UpdateVisibilityState(frame);
74}
75
76}  // namespace prerender
77