Add support for complete buffer discards.

Add support for complete buffer discards.

Per discussion, allows kInfiniteDuration() for the front DiscardPadding
value.  When there's no decoder delay, this ensures accuracy when
discarding.  If decoder delay is present, the code falls back to using
the duration as an estimation.

BUG=371633
TEST=new unittests
NOTRY=true
R=wolenetz@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=271928

[wolenetz, 2014-05-21 01:43:02]

lgtm % nits

https://codereview.chromium.org/293053005/diff/1/media/base/audio_discard_hel...
File media/base/audio_discard_helper_unittest.cc (right):

https://codereview.chromium.org/293053005/diff/1/media/base/audio_discard_hel...
media/base/audio_discard_helper_unittest.cc:448: TEST(AudioDiscardHelperTest,
CompleteDiscardWithDecoderDelay) {
nit: s/With/WithInitialDiscardAnd/

https://codereview.chromium.org/293053005/diff/1/media/base/audio_discard_hel...
media/base/audio_discard_helper_unittest.cc:471: // Plus 5ms off the front of
the second buffer.
nit: s/Plus/Verify/ && s/./ is discarded./

https://codereview.chromium.org/293053005/diff/1/media/base/decoder_buffer.h
File media/base/decoder_buffer.h (right):

https://codereview.chromium.org/293053005/diff/1/media/base/decoder_buffer.h#...
media/base/decoder_buffer.h:112: // first value indicates the entire buffer
should be discarded.
nit: s/./, in which case the second value must be base::TimeDelta()./

[DaleCurtis, 2014-05-21 02:23:25]

https://codereview.chromium.org/293053005/diff/1/media/base/audio_discard_hel...
File media/base/audio_discard_helper_unittest.cc (right):

https://codereview.chromium.org/293053005/diff/1/media/base/audio_discard_hel...
media/base/audio_discard_helper_unittest.cc:448: TEST(AudioDiscardHelperTest,
CompleteDiscardWithDecoderDelay) {
On 2014/05/21 01:43:02, wolenetz wrote:
> nit: s/With/WithInitialDiscardAnd/

Done.

https://codereview.chromium.org/293053005/diff/1/media/base/audio_discard_hel...
media/base/audio_discard_helper_unittest.cc:471: // Plus 5ms off the front of
the second buffer.
On 2014/05/21 01:43:02, wolenetz wrote:
> nit: s/Plus/Verify/ && s/./ is discarded./

Done.

https://codereview.chromium.org/293053005/diff/1/media/base/decoder_buffer.h
File media/base/decoder_buffer.h (right):

https://codereview.chromium.org/293053005/diff/1/media/base/decoder_buffer.h#...
media/base/decoder_buffer.h:112: // first value indicates the entire buffer
should be discarded.
On 2014/05/21 01:43:02, wolenetz wrote:
> nit: s/./, in which case the second value must be base::TimeDelta()./

Done.

[DaleCurtis, 2014-05-21 02:23:47]

The CQ bit was checked by dalecurtis@chromium.org

[commit-bot: I haz the power, 2014-05-21 02:24:12]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/dalecurtis@chromium.org/293053005/20001

[DaleCurtis, 2014-05-21 17:56:57]

The CQ bit was unchecked by dalecurtis@chromium.org

[DaleCurtis, 2014-05-21 17:57:06]

The CQ bit was checked by dalecurtis@chromium.org

[DaleCurtis, 2014-05-21 18:27:58]

Committed patchset #2 manually as r271928 (presubmit successful).