Add callback in VideoDecoder and AudioDecoder to return decoded frames.

Previously decoded frames were returned using the DecodeCB callback,
which is called in response to Decode(). This didn't work very well,
particularly for GPU decoder, because decode buffers do not always map
to decoded frames 1 to 1.

BUG=338529

Review URL: https://codereview.chromium.org/297553002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@276344 0039d316-1c4b-4281-b951-d872f2087c98

• media/base/audio_decoder.cc[diff]
• media/base/audio_decoder.h[diff]
• media/base/mock_filters.h[diff]
• media/base/video_decoder.cc[diff]
• media/base/video_decoder.h[diff]
• media/filters/audio_decoder_selector_unittest.cc[diff]
• media/filters/audio_renderer_impl_unittest.cc[diff]
• media/filters/decoder_selector.cc[diff]
• media/filters/decoder_selector.h[diff]
• media/filters/decoder_stream.cc[diff]
• media/filters/decoder_stream.h[diff]
• media/filters/decoder_stream_traits.cc[diff]
• media/filters/decoder_stream_traits.h[diff]
• media/filters/decrypting_audio_decoder.cc[diff]
• media/filters/decrypting_audio_decoder.h[diff]
• media/filters/decrypting_audio_decoder_unittest.cc[diff]
• media/filters/decrypting_video_decoder.cc[diff]
• media/filters/decrypting_video_decoder.h[diff]
• media/filters/decrypting_video_decoder_unittest.cc[diff]
• media/filters/fake_video_decoder.cc[diff]
• media/filters/fake_video_decoder.h[diff]
• media/filters/fake_video_decoder_unittest.cc[diff]
• media/filters/ffmpeg_audio_decoder.cc[diff]
• media/filters/ffmpeg_audio_decoder.h[diff]
• media/filters/ffmpeg_audio_decoder_unittest.cc[diff]
• media/filters/ffmpeg_video_decoder.cc[diff]
• media/filters/ffmpeg_video_decoder.h[diff]
• media/filters/ffmpeg_video_decoder_unittest.cc[diff]
• media/filters/gpu_video_decoder.cc[diff]
• media/filters/gpu_video_decoder.h[diff]
• media/filters/opus_audio_decoder.cc[diff]
• media/filters/opus_audio_decoder.h[diff]
• media/filters/opus_audio_decoder_unittest.cc[diff]
• media/filters/video_decoder_selector_unittest.cc[diff]
• media/filters/video_frame_stream_unittest.cc[diff]
• media/filters/video_renderer_impl_unittest.cc[diff]
• media/filters/vpx_video_decoder.cc[diff]
• media/filters/vpx_video_decoder.h[diff]