Change MediaFilter::Stop() to accept a callback so that Stop() is asynchronous.

media/base/filter_host.h

 // Copyright (c) 2010 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.
 
 // FilterHost describes an interface for individual filters to access and
 // modify global playback information.  Every filter is given a filter host
 // reference as part of initialization.
 //
 // This interface is intentionally verbose to cover the needs for the different
 // types of filters (see media/base/filters.h for filter definitionss).  Filters
 // typically use parts of the interface that are relevant to their function.
 // For example, an audio renderer filter typically calls SetTime as it feeds
 // data to the audio hardware.  A video renderer filter typically calls GetTime
 // to synchronize video with audio.  An audio and video decoder would typically
 // have no need to call either SetTime or GetTime.
 
 #ifndef MEDIA_BASE_FILTER_HOST_H_
 #define MEDIA_BASE_FILTER_HOST_H_
 
 #include "base/task.h"
 #include "media/base/filters.h"
 #include "media/base/pipeline.h"
 
 namespace media {
 
 class FilterHost {
  public:
   // Stops execution of the pipeline due to a fatal error.  Do not call this
-  // method with PIPELINE_OK or PIPELINE_STOPPING (used internally by pipeline).
+  // method with PIPELINE_OK.
   virtual void SetError(PipelineError error) = 0;
 
   // Gets the current time in microseconds.
   virtual base::TimeDelta GetTime() const = 0;
 
   // Gets the duration in microseconds.
   virtual base::TimeDelta GetDuration() const = 0;
 
   // Updates the current time.  Other filters should poll to examine the updated
   // time.
@@ skipping 40 matching lines @@
   // Gets the byte offset at which the client is requesting the video.
   virtual int64 GetCurrentReadPosition() = 0;
 
  protected:
   virtual ~FilterHost() {}
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_FILTER_HOST_H_