Merge GpuCommandBufferMsg_SetLatencyInfo into GpuCommandBufferMsg_AsyncFlush

Merge GpuCommandBufferMsg_SetLatencyInfo into GpuCommandBufferMsg_AsyncFlush

GpuCommandBufferMsg_SetLatencyInfo is used to send current frame's latencyinfo
to gpu. We can piggyback the latencyinfo in GpuCommandBufferMsg_AsyncFlush so
eliminate the extra IPC.

BUG=404650
TEST=check trace that now GLRenderer::SwapBuffers only sends 2 IPC messages,
     i.e. AsyncFlush and Echo. And LatencyInfo tracking is still working.

Committed: https://crrev.com/ef0850f4739a1d3b440495f318dc349c162edf4e
Cr-Commit-Position: refs/heads/master@{#294895}

[Yufeng Shen (Slow to review), 2014-09-11 17:58:48]

miletus@chromium.org changed reviewers:
+ jbauman@chromium.org

[jbauman, 2014-09-11 18:54:12]

lgtm

[Yufeng Shen (Slow to review), 2014-09-11 19:42:32]

The CQ bit was checked by miletus@chromium.org

[commit-bot: I haz the power, 2014-09-11 19:56:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/564903002/1

[commit-bot: I haz the power, 2014-09-11 20:38:15]

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

[commit-bot: I haz the power, 2014-09-11 20:38:16]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[Yufeng Shen (Slow to review), 2014-09-11 20:41:00]

miletus@chromium.org changed reviewers:
+ jln@chromium.org

[Yufeng Shen (Slow to review), 2014-09-11 20:42:03]

+ jln@ for content/common/gpu/gpu_messages.h


John,

I also removed the ShallowFlushCHROMIUM() call from
GpuBrowserCompositorOutputSurface::SwapBuffers and
CompositorOutputSurface::SwapBuffers

[jln (very slow on Chromium), 2014-09-15 19:31:34]

content/common/gpu/gpu_messages.h lgtm, sorry for the delay.

[Yufeng Shen (Slow to review), 2014-09-15 19:33:26]

The CQ bit was checked by miletus@chromium.org

[commit-bot: I haz the power, 2014-09-15 19:34:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/564903002/20001

[commit-bot: I haz the power, 2014-09-15 21:32:35]

Committed patchset #2 (id:20001) as cd843743be9331e48372909ad73aa6dfe956686b

[commit-bot: I haz the power, 2014-09-15 21:44:25]

Patchset 2 (id:??) landed as
https://crrev.com/ef0850f4739a1d3b440495f318dc349c162edf4e
Cr-Commit-Position: refs/heads/master@{#294895}