WeakPtr destruction order cleanup: media edition.

content/renderer/media/video_capture_impl_manager.h

 // 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.
 
 // VideoCaptureImplManager owns VideoCaptureImpl objects. Clients who
 // want access to a video capture device call UseDevice() to get a handle
 // to VideoCaptureImpl.
 //
 // THREADING
 //
@@ skipping 83 matching lines @@
   void UnrefDevice(media::VideoCaptureSessionId id);
 
   // The int is used to count clients of the corresponding VideoCaptureImpl.
   typedef std::map<media::VideoCaptureSessionId,
                    std::pair<int, linked_ptr<VideoCaptureImpl> > >
       VideoCaptureDeviceMap;
   VideoCaptureDeviceMap devices_;
 
   scoped_refptr<VideoCaptureMessageFilter> filter_;
 
-  // Following two members are bound to the render thread.
+  // Bound to the render thread.
+  base::ThreadChecker thread_checker_;
+
+  // Bound to the render thread.
+  // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<VideoCaptureImplManager> weak_factory_;
-  base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(VideoCaptureImplManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_VIDEO_CAPTURE_IMPL_MANAGER_H_