Fixit: Move tab and desktop capture code to new location.

content/browser/renderer_host/media/web_contents_tracker.h

-// Copyright (c) 2013 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.
-//
-// Given a starting render_process_id and render_view_id, the WebContentsTracker
-// tracks RenderViewHost instance swapping during the lifetime of a WebContents
-// instance.  This is used when mirroring tab video and audio so that user
-// navigations, crashes, etc., during a tab's lifetime allow the capturing code
-// to remain active on the current/latest RenderView.
-//
-// Threading issues: Start(), Stop() and the ChangeCallback are invoked on the
-// same thread.  This can be any thread, and the decision is locked-in by
-// WebContentsTracker when Start() is called.
-
-#ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_WEB_CONTENTS_TRACKER_H_
-#define CONTENT_BROWSER_RENDERER_HOST_MEDIA_WEB_CONTENTS_TRACKER_H_
-
-#include "base/callback.h"
-#include "base/memory/ref_counted.h"
-#include "content/common/content_export.h"
-#include "content/public/browser/web_contents_observer.h"
-
-namespace base {
-class MessageLoopProxy;
-}
-
-namespace content {
-
-class CONTENT_EXPORT WebContentsTracker
-    : public base::RefCountedThreadSafe<WebContentsTracker>,
-      public WebContentsObserver {
- public:
-  WebContentsTracker();
-
-  // Callback for whenever the target is swapped.  The callback is also invoked
-  // with both arguments set to MSG_ROUTING_NONE to indicate tracking will not
-  // continue (i.e., the WebContents instance was not found or has been
-  // destroyed).
-  typedef base::Callback<void(int render_process_id, int render_view_id)>
-      ChangeCallback;
-
-  // Start tracking.  The last-known |render_process_id| and |render_view_id|
-  // are provided, and the given callback is invoked asynchronously one or more
-  // times.  The callback will be invoked on the same thread calling Start().
-  virtual void Start(int render_process_id, int render_view_id,
-                     const ChangeCallback& callback);
-
-  // Stop tracking.  Once this method returns, the callback is guaranteed not to
-  // be invoked again.
-  virtual void Stop();
-
- protected:
-  friend class base::RefCountedThreadSafe<WebContentsTracker>;
-  virtual ~WebContentsTracker();
-
- private:
-  // Reads the render_process_id/render_view_id from the current WebContents
-  // instance and then invokes the callback.
-  void OnWebContentsChangeEvent();
-
-  // Called on the thread that Start()/Stop() are called on, check whether the
-  // callback is still valid and, if so, invoke it.
-  void MaybeDoCallback(int render_process_id, int render_view_id);
-
-  // Look-up the current WebContents instance associated with the given
-  // |render_process_id| and |render_view_id| and begin observing it.
-  void LookUpAndObserveWebContents(int render_process_id,
-                                   int render_view_id);
-
-  // WebContentsObserver overrides to react to events of interest.
-  virtual void RenderViewReady() OVERRIDE;
-  virtual void AboutToNavigateRenderView(RenderViewHost* render_view_host)
-      OVERRIDE;
-  virtual void DidNavigateMainFrame(const LoadCommittedDetails& details,
-                                    const FrameNavigateParams& params) OVERRIDE;
-  virtual void WebContentsDestroyed(WebContents* web_contents) OVERRIDE;
-
-  scoped_refptr<base::MessageLoopProxy> message_loop_;
-  ChangeCallback callback_;
-
-  DISALLOW_COPY_AND_ASSIGN(WebContentsTracker);
-};
-
-}  // namespace content
-
-#endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_WEB_CONTENTS_TRACKER_H_