Replace erroneous use of base::Time with base::TimeTicks throughout media code.

Replace erroneous use of base::Time with base::TimeTicks throughout media code.

This change corrects all the "low-hanging fruit," leaving the VideoCaptureDevice interface and MediaLog (?) as separate changes; as they are referenced throughout other components.

Added a PRESUBMIT.py script for media/ code that will scan future code changes for use of base::Time (or base::Clock/DefaultClock) and prompt the developer with a warning explaining that clock skew is a serious and subtle source of bugs.

Testing: Ran all media_unittests and content_unittests.  Manually ran through demo sites that utilize all of the following (on all of Win/Mac/Linux): 1. HTML5 audio and video; 2. PPAPI Flash video; 3. WebAudio API; 4. WebRTC; 5. Tab Capture API.

BUG=247881
TEST=media_unittests, content_unittests, manual confirmation of major media use cases

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=206206

[miu, 2013-06-12 22:24:53]

Andrew/Dale,

Please review everything.  Should be a quick one since base::TimeTicks is pretty
much a drop-in replacement for base::Time.  All the code I changed only used
base::Time to track the passage of time (i.e., no code needs to map
base::TimeTicks to a user-displayable date/time).

I have an open question around whether media::MediaLogEvent should use
base::Time or base::TimeTicks, so I left it alone in this change.

Thanks,
Yuri

[DaleCurtis, 2013-06-13 00:23:31]

lgtm % nits. I defer to scherkus@ for the presubmit. I'd worry about false
positives..

https://codereview.chromium.org/16823003/diff/1/media/PRESUBMIT.py
File media/PRESUBMIT.py (right):

https://codereview.chromium.org/16823003/diff/1/media/PRESUBMIT.py#newcode1
media/PRESUBMIT.py:1: # Copyright (c) 2013 The Chromium Authors. All rights
reserved.
2013 license is w/o (c).

https://codereview.chromium.org/16823003/diff/1/media/filters/audio_renderer_...
File media/filters/audio_renderer_impl.h (right):

https://codereview.chromium.org/16823003/diff/1/media/filters/audio_renderer_...
media/filters/audio_renderer_impl.h:135: base::TimeTicks time_now);
const & both

[miu, 2013-06-13 01:42:08]

https://codereview.chromium.org/16823003/diff/1/media/PRESUBMIT.py
File media/PRESUBMIT.py (right):

https://codereview.chromium.org/16823003/diff/1/media/PRESUBMIT.py#newcode1
media/PRESUBMIT.py:1: # Copyright (c) 2013 The Chromium Authors. All rights
reserved.
On 2013/06/13 00:23:32, DaleCurtis wrote:
> 2013 license is w/o (c).

Done.

https://codereview.chromium.org/16823003/diff/1/media/filters/audio_renderer_...
File media/filters/audio_renderer_impl.h (right):

https://codereview.chromium.org/16823003/diff/1/media/filters/audio_renderer_...
media/filters/audio_renderer_impl.h:135: base::TimeTicks time_now);
On 2013/06/13 00:23:32, DaleCurtis wrote:
> const & both

Done.

[scherkus (not reviewing), 2013-06-13 01:47:47]

LGTM

let's give the presubmit a shot -- if we find it's too slow / too many false
positives / etc. we can either tweak it or remove it

[miu, 2013-06-13 02:28:47]

Thanks for the review.

Yep.  I'm pretty sure false positives from the presubmit will be near-zero.  I
made sure (also for efficiency's sake) that the presubmit only examines
new/changed lines of C++ code.

[commit-bot: I haz the power, 2013-06-13 03:11:33]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/miu@chromium.org/16823003/8002

[commit-bot: I haz the power, 2013-06-13 08:01:16]

Retried try job too often on chromium_presubmit for step(s) presubmit
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=chromium_p...

[commit-bot: I haz the power, 2013-06-13 19:30:51]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/miu@chromium.org/16823003/22001

[commit-bot: I haz the power, 2013-06-13 23:20:46]

Change committed as 206206