Make Callback::Reset() return a copy to support use-cases where Run() ends up modifying |*this|.

content/renderer/media/capture_video_decoder.cc

 // 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.
 
 #include "content/renderer/media/capture_video_decoder.h"
 
 #include "base/bind.h"
 #include "content/renderer/media/video_capture_impl_manager.h"
 #include "media/base/filter_host.h"
 #include "media/base/limits.h"
@@ skipping 184 matching lines @@
 
   cb.Run(media::PIPELINE_OK);
   state_ = kNormal;
 }
 
 void CaptureVideoDecoder::OnStoppedOnDecoderThread(
     media::VideoCapture* capture) {
   DVLOG(1) << "OnStoppedOnDecoderThread";
   DCHECK(message_loop_proxy_->BelongsToCurrentThread());
   if (!pending_stop_cb_.is_null())
-    media::ResetAndRunCB(&pending_stop_cb_);
+    pending_stop_cb_.ResetAndRun();
   vc_manager_->RemoveDevice(video_stream_id_, this);
 }
 
 void CaptureVideoDecoder::OnDeviceInfoReceivedOnDecoderThread(
     media::VideoCapture* capture,
     const media::VideoCaptureParams& device_info) {
   DCHECK(message_loop_proxy_->BelongsToCurrentThread());
   if (device_info.width != natural_size_.width() ||
       device_info.height != natural_size_.height()) {
     natural_size_.SetSize(device_info.width, device_info.height);
@@ skipping 61 matching lines @@
   capture->FeedBuffer(buf);
 }
 
 void CaptureVideoDecoder::DeliverFrame(
     const scoped_refptr<media::VideoFrame>& video_frame) {
   // Reset the callback before running to protect against reentrancy.
   ReadCB read_cb = read_cb_;
   read_cb_.Reset();
   read_cb.Run(video_frame);
 }