WeakPtr destruction order cleanup: media edition.

media/cast/video_sender/external_video_encoder.h

 // Copyright 2014 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.
 
 #ifndef MEDIA_CAST_VIDEO_SENDER_EXTERNAL_VIDEO_ENCODER_H_
 #define MEDIA_CAST_VIDEO_SENDER_EXTERNAL_VIDEO_ENCODER_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "media/cast/cast_config.h"
@@ skipping 52 matching lines @@
 
   bool encoder_active_;
   bool key_frame_requested_;
   bool skip_next_frame_;
   int skip_count_;
 
   scoped_refptr<LocalVideoEncodeAcceleratorClient> video_accelerator_client_;
   scoped_refptr<base::SingleThreadTaskRunner> encoder_task_runner_;
 
   // Weak pointer factory for posting back LocalVideoEncodeAcceleratorClient
-  // notifications to ExternalVideoEncoder.
+  // notifications to ExternalVideoEncoder.  NOTE: This must always be last so
+  // it's invalidated before other member variables might be accessed.
   base::WeakPtrFactory<ExternalVideoEncoder> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ExternalVideoEncoder);
 };
 
 }  // namespace cast
 }  // namespace media
 
 #endif  // MEDIA_CAST_VIDEO_SENDER_EXTERNAL_VIDEO_ENCODER_H_