1// Copyright (c) 2013 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// Given a starting render_process_id and main_render_frame_id, the 6// WebContentsTracker tracks changes to the active RenderFrameHost tree during 7// the lifetime of a WebContents instance. This is used when mirroring tab 8// video and audio so that user navigations, crashes, iframes, etc., during a 9// tab's lifetime allow the capturing code to remain active on the 10// current/latest render frame tree. 11// 12// Threading issues: Start(), Stop() and the ChangeCallback are invoked on the 13// same thread. This can be any thread, and the decision is locked-in by 14// WebContentsTracker when Start() is called. 15 16#ifndef CONTENT_BROWSER_MEDIA_CAPTURE_WEB_CONTENTS_TRACKER_H_ 17#define CONTENT_BROWSER_MEDIA_CAPTURE_WEB_CONTENTS_TRACKER_H_ 18 19#include "base/callback.h" 20#include "base/memory/ref_counted.h" 21#include "content/common/content_export.h" 22#include "content/public/browser/web_contents_observer.h" 23 24namespace base { 25class MessageLoopProxy; 26} 27 28namespace content { 29 30class RenderWidgetHost; 31 32class CONTENT_EXPORT WebContentsTracker 33 : public base::RefCountedThreadSafe<WebContentsTracker>, 34 public WebContentsObserver { 35 public: 36 // If |track_fullscreen_rwh| is true, the ChangeCallback will be run when a 37 // WebContents shows/destroys a fullscreen RenderWidgetHost view. If false, 38 // fullscreen events are ignored. Specify true for video tab capture and 39 // false for audio tab capture. 40 explicit WebContentsTracker(bool track_fullscreen_rwh); 41 42 // Callback to indicate a new RenderWidgetHost should be targeted for capture. 43 // This is also invoked with NULL to indicate tracking will not continue 44 // (i.e., the WebContents instance was not found or has been destroyed). 45 typedef base::Callback<void(RenderWidgetHost* rwh)> ChangeCallback; 46 47 // Start tracking. The last-known |render_process_id| and 48 // |main_render_frame_id| are provided, and |callback| will be run once to 49 // indicate the current capture target (this may occur during the invocation 50 // of Start(), or in the future). The callback will be invoked on the same 51 // thread calling Start(). 52 virtual void Start(int render_process_id, int main_render_frame_id, 53 const ChangeCallback& callback); 54 55 // Stop tracking. Once this method returns, the callback is guaranteed not to 56 // be invoked again. 57 virtual void Stop(); 58 59 // Current target. This must only be called on the UI BrowserThread. 60 RenderWidgetHost* GetTargetRenderWidgetHost() const; 61 62 protected: 63 friend class base::RefCountedThreadSafe<WebContentsTracker>; 64 virtual ~WebContentsTracker(); 65 66 private: 67 // Determine the target RenderWidgetHost and, if different from that last 68 // reported, runs the ChangeCallback on the appropriate thread. If 69 // |force_callback_run| is true, the ChangeCallback is run even if the 70 // RenderWidgetHost has not changed. 71 void OnPossibleTargetChange(bool force_callback_run); 72 73 // Called on the thread that Start()/Stop() are called on. Checks whether the 74 // callback is still valid and, if so, runs it. 75 void MaybeDoCallback(RenderWidgetHost* rwh); 76 77 // Look-up the current WebContents instance associated with the given 78 // |render_process_id| and |main_render_frame_id| and begin observing it. 79 void StartObservingWebContents(int render_process_id, 80 int main_render_frame_id); 81 82 // WebContentsObserver overrides: According to web_contents_observer.h, these 83 // two method overrides are all that is necessary to track the set of active 84 // RenderFrameHosts. 85 virtual void RenderFrameDeleted(RenderFrameHost* render_frame_host) OVERRIDE; 86 virtual void RenderFrameHostChanged(RenderFrameHost* old_host, 87 RenderFrameHost* new_host) OVERRIDE; 88 89 // WebContentsObserver override to notify the client that the capture target 90 // has been permanently lost. 91 virtual void WebContentsDestroyed() OVERRIDE; 92 93 // WebContentsObserver overrides to notify the client that the capture target 94 // may have changed due to a separate fullscreen widget shown/destroyed. 95 virtual void DidShowFullscreenWidget(int routing_id) OVERRIDE; 96 virtual void DidDestroyFullscreenWidget(int routing_id) OVERRIDE; 97 98 // If true, the client is interested in the showing/destruction of fullscreen 99 // RenderWidgetHosts. 100 const bool track_fullscreen_rwh_; 101 102 // MessageLoop corresponding to the thread that called Start(). 103 scoped_refptr<base::MessageLoopProxy> message_loop_; 104 105 // Callback to run when the target RenderWidgetHost has changed. 106 ChangeCallback callback_; 107 108 // Pointer to the RenderWidgetHost provided in the last run of |callback_|. 109 // This is used to eliminate duplicate callback runs. 110 RenderWidgetHost* last_target_; 111 112 DISALLOW_COPY_AND_ASSIGN(WebContentsTracker); 113}; 114 115} // namespace content 116 117#endif // CONTENT_BROWSER_MEDIA_CAPTURE_WEB_CONTENTS_TRACKER_H_ 118