CrOS: Look for consistency between successive vsync intervals.

CrOS: Look for consistency between successive vsync intervals.

Currently we report computed vsync intervals based on if they are in
an expected range and silently drop otherwise. The disadvantage with this
is that we're probably reporting noise caused by configuration changes
(monitor reconfiguration or moving a window between monitors). We may
also be papering over driver bugs.

Instead, we look for consistency between successive computed intervals
as a way of validating that there hasn't been a configuration change. In
this case, we can be more aggressive in error reporting to find driver bugs
(crash instead of silently drop).

BUG=221701
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=193386

[jonathan.backer, 2013-04-09 17:44:05]

I'd like to crash rather than just log with the understanding that I will switch
back to just log before if we're still crashing.

[jonathan.backer, 2013-04-09 18:30:35]

On 2013/04/09 17:44:05, jonathan.backer wrote:
> I'd like to crash rather than just log with the understanding that I will
switch
> back to just log before if we're still crashing.

s/before/before branch/

[piman, 2013-04-10 01:17:02]

LGTM - TBH I'm kinda sad that we need all that logic, and wish we could
GetMscRate in the driver instead, but I don't see another short term way.

[commit-bot: I haz the power, 2013-04-10 12:24:06]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/backer@chromium.org/13861016/2001

[commit-bot: I haz the power, 2013-04-10 15:19:49]

Change committed as 193386