Workaround for race condition between audio host and renderer

Windows-only change -- issue is worst on Windows because of pre-buffering. On Linux problem is much milder, and on Mac we cannot yield high-priority audio thread...

Very short-term change: while working on proper long-term solution,
workaround for race condition that causes clicks and bad audio stream.
Yield if reader was called too quickly after previous call, as there
are good chances renderer thread did not fill the buffer yet.

BUG=http://code.google.com/p/chromium/issues/detail?id=61022

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=99236

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=101231

[scherkus (not reviewing), 2011-09-01 03:16:48]

Can you update CL description with suitable BUG= number?

LGTM w/ nits

http://codereview.chromium.org/7755001/diff/6001/content/browser/renderer_hos...
File content/browser/renderer_host/media/audio_sync_reader.cc (right):

http://codereview.chromium.org/7755001/diff/6001/content/browser/renderer_hos...
content/browser/renderer_host/media/audio_sync_reader.cc:17:
previous_call_time_(base::Time()) {
no need to use declare this as you're using default ctor

http://codereview.chromium.org/7755001/diff/6001/content/browser/renderer_hos...
content/browser/renderer_host/media/audio_sync_reader.cc:35: // cannot change
the API, so we yield if previos call was too recently.
previos -> previous
too recently -> too recent

http://codereview.chromium.org/7755001/diff/6001/content/browser/renderer_hos...
content/browser/renderer_host/media/audio_sync_reader.cc:40: (base::Time::Now()
- previous_call_time_).InMilliseconds() < 10) {
what's 10 ?

care to make it a constant?

http://codereview.chromium.org/7755001/diff/6001/media/audio/audio_util.h
File media/audio/audio_util.h (right):

http://codereview.chromium.org/7755001/diff/6001/media/audio/audio_util.h#new...
media/audio/audio_util.h:95: void SetUnknownDataSize(base::SharedMemory*
shared_memory,
you'll need to add MEDIA_EXPORT for the shared component build as these
functions are used by src/content

[commit-bot: I haz the power, 2011-09-01 18:38:10]

Try job failure for 7755001-11001 (retry) on mac for step "compile" (clobber
build).
It's a second try, previously, step "compile" failed.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=mac&number...

[commit-bot: I haz the power, 2011-09-01 20:16:59]

Change committed as 99236

[commit-bot: I haz the power, 2011-09-15 02:35:49]

Change committed as 101231