Fix potential deadlock between Pipeline and VideoRendererImpl.

media/base/pipeline.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 "media/base/pipeline.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/callback.h"
@@ skipping 387 matching lines @@
       &Demuxer::Seek, base::Unretained(demuxer_), seek_timestamp));
 
   pending_callbacks_ = SerialRunner::Run(bound_fns, done_cb);
 }
 
 void Pipeline::DoStop(const PipelineStatusCB& done_cb) {
   DVLOG(2) << __FUNCTION__;
   DCHECK(task_runner_->BelongsToCurrentThread());
   DCHECK(!pending_callbacks_.get());
 
+  // TODO(scherkus): Enforce that Renderer is only called on a single thread,
+  // even for accessing media time http://crbug.com/370634
+  scoped_ptr<Renderer> renderer;
   {
     base::AutoLock auto_lock(lock_);
-    renderer_.reset();
+    renderer.swap(renderer_);
   }
+  renderer.reset();
   text_renderer_.reset();
 
   if (demuxer_) {
     demuxer_->Stop();
     demuxer_ = NULL;
   }
 
   task_runner_->PostTask(FROM_HERE, base::Bind(done_cb, PIPELINE_OK));
 }
 
@@ skipping 282 matching lines @@
   metadata_cb_.Run(metadata);
 }
 
 void Pipeline::BufferingStateChanged(BufferingState new_buffering_state) {
   DVLOG(1) << __FUNCTION__ << "(" << new_buffering_state << ") ";
   DCHECK(task_runner_->BelongsToCurrentThread());
   buffering_state_cb_.Run(new_buffering_state);
 }
 
 }  // namespace media