content/browser/media/capture/web_contents_tracker.h

   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
  24 namespace base {
  25 class MessageLoopProxy;
  26 }
  27
  28 namespace content {
  29
  30 class RenderWidgetHost;
  31
  32 class 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   ~WebContentsTracker() override;
  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   void RenderFrameDeleted(RenderFrameHost* render_frame_host) override;
  86   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   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   void DidShowFullscreenWidget(int routing_id) override;
  96   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_