Allow AudioRendererMixerInputs to be restarted after stopped.

Allow AudioRendererMixerInputs to be restarted after stopped.

We probably shouldn't allow this, but it's currently relied upon by the
WebAudio code and cleaning it up is a big deal: http://crbug.com/151051.

The AudioRendererSink interface does not specify that after Stop() the
sink can no longer be used.  All other sinks allow restart, so this is
just keeping with the pace.

In http://crrev.com/280502 I conflated the one-stop-only mechanics of
AudioRenderer:Stop() with those of AudioRendererSink::Stop().  This
patch reverts that mistake while keeping the fixes for the original
issue.

BUG=389204, 390977
TEST=new unittest.

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=282481

[rileya (GONE FROM CHROMIUM), 2014-07-10 19:12:43]

lgtm + a couple comments

https://codereview.chromium.org/381823003/diff/1/media/base/audio_renderer_mi...
File media/base/audio_renderer_mixer_input.cc (right):

https://codereview.chromium.org/381823003/diff/1/media/base/audio_renderer_mi...
media/base/audio_renderer_mixer_input.cc:31: void
AudioRendererMixerInput::Initialize(
Initialize() doesn't seem to do much anymore. After we disallow multiple
Start/Stops, can we merge Initialize() and Start()?

https://codereview.chromium.org/381823003/diff/1/media/base/audio_renderer_mi...
media/base/audio_renderer_mixer_input.cc:71: DCHECK(initialized_);
Maybe DCHECK(mixer_) here?

https://codereview.chromium.org/381823003/diff/1/media/base/audio_renderer_mi...
media/base/audio_renderer_mixer_input.cc:81: DCHECK(initialized_);
ditto

[DaleCurtis, 2014-07-10 19:18:55]

https://codereview.chromium.org/381823003/diff/1/media/base/audio_renderer_mi...
File media/base/audio_renderer_mixer_input.cc (right):

https://codereview.chromium.org/381823003/diff/1/media/base/audio_renderer_mi...
media/base/audio_renderer_mixer_input.cc:31: void
AudioRendererMixerInput::Initialize(
On 2014/07/10 19:12:42, rileya wrote:
> Initialize() doesn't seem to do much anymore. After we disallow multiple
> Start/Stops, can we merge Initialize() and Start()?

Unfortunately it's a common interface used throughout the media pipeline, so we
can't really merge it.  Other implementers do more or less in each of those
functions.

https://codereview.chromium.org/381823003/diff/1/media/base/audio_renderer_mi...
media/base/audio_renderer_mixer_input.cc:71: DCHECK(initialized_);
On 2014/07/10 19:12:43, rileya wrote:
> Maybe DCHECK(mixer_) here?

Done.

https://codereview.chromium.org/381823003/diff/1/media/base/audio_renderer_mi...
media/base/audio_renderer_mixer_input.cc:81: DCHECK(initialized_);
On 2014/07/10 19:12:43, rileya wrote:
> ditto

Done.

[DaleCurtis, 2014-07-10 19:19:03]

The CQ bit was checked by dalecurtis@chromium.org

[commit-bot: I haz the power, 2014-07-10 19:21:34]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/dalecurtis@chromium.org/381823003/20001

[commit-bot: I haz the power, 2014-07-10 21:48:06]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  android_dbg_triggered_tests on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_dbg_triggered...)
  mac_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/mac_chromium_rel/buil...)

[commit-bot: I haz the power, 2014-07-11 00:37:09]

Change committed as 282481