Add a lot of Pipeline tests to cover stopping/error handling while in a variety of states.

media/base/mock_filters.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.
 //
 // A new breed of mock media filters, this time using gmock!  Feel free to add
 // actions if you need interesting side-effects.
 //
 // Don't forget you can use StrictMock<> and NiceMock<> if you want the mock
 // filters to fail the test or do nothing when an unexpected method is called.
 // http://code.google.com/p/googlemock/wiki/CookBook#Nice_Mocks_and_Strict_Mocks
@@ skipping 256 matching lines @@
  private:
   scoped_refptr<MockDemuxer> demuxer_;
   scoped_refptr<MockVideoDecoder> video_decoder_;
   scoped_refptr<MockAudioDecoder> audio_decoder_;
   scoped_refptr<MockVideoRenderer> video_renderer_;
   scoped_refptr<MockAudioRenderer> audio_renderer_;
 
   DISALLOW_COPY_AND_ASSIGN(MockFilterCollection);
 };
 
-// Helper gmock action that calls SetError() on behalf of the provided filter.
-ACTION_P2(SetError, filter, error) {
-  filter->host()->SetError(error);
-}
-
 ACTION(RunClosure) {
   arg0.Run();
 }
 
 // Helper mock statistics callback.
 class MockStatisticsCB {
  public:
   MockStatisticsCB();
   ~MockStatisticsCB();
 
   MOCK_METHOD1(OnStatistics, void(const media::PipelineStatistics& statistics));
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_MOCK_FILTERS_H_