Enable FCM on mac and threaded-compositing on Windows on Canary/Dev

Enable force-compositing-mode by default on mac and threaded-compositing on windows for Canary and Dev channels to collect some more data while the page-cycler regressions are being worked out (see issue http://code.google.com/p/chromium/issues/detail?id=152355) .

It cancels out all other field trial experiments to simplify things.

BUG=128385, 146861, 143809, 128387
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=164480

[Vangelis Kokkevis, 2012-10-25 00:28:14]

Nico, can you please review?

[Nico, 2012-10-26 01:15:10]

lgtm stamp

https://codereview.chromium.org/11267026/diff/1/chrome/browser/chrome_gpu_uti...
File chrome/browser/chrome_gpu_util.cc (left):

https://codereview.chromium.org/11267026/diff/1/chrome/browser/chrome_gpu_uti...
chrome/browser/chrome_gpu_util.cc:166: if (channel ==
chrome::VersionInfo::CHANNEL_STABLE ||
Huh, this used to be on by default on stable and beta, but not on dev or
canary?!

https://codereview.chromium.org/11267026/diff/1/chrome/browser/chrome_gpu_uti...
File chrome/browser/chrome_gpu_util.cc (right):

https://codereview.chromium.org/11267026/diff/1/chrome/browser/chrome_gpu_uti...
chrome/browser/chrome_gpu_util.cc:166: force_compositing_mode_probability = 3;
nit: s/3/kDivisor/ (like last time)

[Vangelis Kokkevis, 2012-10-26 01:35:46]

Thank you, Nico. I'm afraid I'm going to forego your lgtm stamp in favor of
turning on threaded compositing and fcm on TOT for canary builds only. We are
still working on page-cycler issues but would like to get more data from the
field on how these modes do otherwise.

Can you please take another look?

[Nico, 2012-10-26 21:45:21]

slgtm

[commit-bot: I haz the power, 2012-10-26 22:20:04]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/vangelis@chromium.org/11267026/16001

[commit-bot: I haz the power, 2012-10-27 01:31:12]

Change committed as 164480