Reland: Use a shared thread for media operations (round 3).

media/base/pipeline.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.
 
 #ifndef MEDIA_BASE_PIPELINE_H_
 #define MEDIA_BASE_PIPELINE_H_
 
 #include <string>
 
 #include "base/gtest_prod_util.h"
@@ skipping 96 matching lines @@
              const PipelineStatusCB& error_cb,
              const PipelineStatusCB& seek_cb,
              const BufferingStateCB& buffering_state_cb,
              const base::Closure& duration_change_cb);
 
   // Asynchronously stops the pipeline, executing |stop_cb| when the pipeline
   // teardown has completed.
   //
   // Stop() must complete before destroying the pipeline. It it permissible to
   // call Stop() at any point during the lifetime of the pipeline.
+  //
+  // It is safe to delete the pipeline during the execution of |stop_cb|.
   void Stop(const base::Closure& stop_cb);
 
   // Attempt to seek to the position specified by time.  |seek_cb| will be
   // executed when the all filters in the pipeline have processed the seek.
   //
   // Clients are expected to call GetMediaTime() to check whether the seek
   // succeeded.
   //
   // It is an error to call this method if the pipeline has not started.
   void Seek(base::TimeDelta time, const PipelineStatusCB& seek_cb);
@@ skipping 315 matching lines @@
   scoped_ptr<SerialRunner> pending_callbacks_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(Pipeline);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_PIPELINE_H_