Enable compositing for will-change GPU hints when hybrid rasterization is enabled

Enable compositing for will-change GPU hints when hybrid rasterization is enabled

This enables compositing for will-change GPU rasterization hints when 
hybrid GPU rasterization is enabled (that is, when running with
--enable-gpu-rasterization). Creating composited layers for such hints
only makes sense when using hybrid rasterization, since such hints are
otherwise ignored.

BUG=329722
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=256829

[jamesr, 2014-03-12 23:21:38]

lgtm

[ajuma, 2014-03-13 01:30:45]

The CQ bit was checked by ajuma@chromium.org

[commit-bot: I haz the power, 2014-03-13 01:31:13]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/ajuma@chromium.org/197473002/20001

[commit-bot: I haz the power, 2014-03-13 01:38:01]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-03-13 01:38:02]

Try jobs failed on following builders:
  tryserver.chromium on win_chromium_compile_dbg

[ajuma, 2014-03-13 01:55:17]

The CQ bit was checked by ajuma@chromium.org

[commit-bot: I haz the power, 2014-03-13 01:55:43]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/ajuma@chromium.org/197473002/20001

[commit-bot: I haz the power, 2014-03-13 03:56:03]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-03-13 03:56:04]

Try jobs failed on following builders:
  tryserver.chromium on linux_chromium_chromeos_clang_dbg

[ajuma, 2014-03-13 13:17:48]

The CQ bit was checked by ajuma@chromium.org

[commit-bot: I haz the power, 2014-03-13 13:17:50]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/ajuma@chromium.org/197473002/20001

[commit-bot: I haz the power, 2014-03-13 15:05:48]

Change committed as 256829