Fix chromium-style compile error that got in the tree since yesterday.

media/base/mock_filters.h

 // Copyright (c) 2011 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 (i.e., copying data to the
 // buffer passed into MockDataSource::Read()).
 //
 // 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.
@@ skipping 302 matching lines @@
 
 // Helper gmock action that calls DisableAudioRenderer() on behalf of the
 // provided filter.
 ACTION_P(DisableAudioRenderer, filter) {
   filter->host()->DisableAudioRenderer();
 }
 
 // Helper mock statistics callback.
 class MockStatisticsCallback {
  public:
+  MockStatisticsCallback();
+  ~MockStatisticsCallback();
+
   MOCK_METHOD1(OnStatistics, void(const media::PipelineStatistics& statistics));
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_MOCK_FILTERS_H_