Read compositor VSync information from platform, when possible

content/renderer/gpu/compositor_output_surface.cc

Index: content/renderer/gpu/compositor_output_surface.cc
diff --git a/content/renderer/gpu/compositor_output_surface.cc b/content/renderer/gpu/compositor_output_surface.cc
index 7cb51996d4fc94e9ac117a4d0302bc010836f7ff..cdcc1c8f16b7bf357427de07b56e4960d91d2681 100644
--- a/content/renderer/gpu/compositor_output_surface.cc
+++ b/content/renderer/gpu/compositor_output_surface.cc
@@ -138,7 +138,8 @@ void CompositorOutputSurface::OnMessageReceived(const IPC::Message& message) {
   if (!HasClient())
     return;
   IPC_BEGIN_MESSAGE_MAP(CompositorOutputSurface, message)
-    IPC_MESSAGE_HANDLER(ViewMsg_UpdateVSyncParameters, OnUpdateVSyncParameters);
+    IPC_MESSAGE_HANDLER(ViewMsg_UpdateVSyncParameters,
+                        OnUpdateVSyncParametersFromView);

[piman, 2014/02/04 04:51:01]

nit: gratuitous rename? Not sure which "FromView" refers to.

[sheu, 2014/02/04 22:01:45]

A little bit convoluted.  See comment in BrowserCompositorOutputSurface.  Short
answer here: because the BrowserCompositorOutputSurface version has been renamed
to OnUpdateVSyncParametersFromGpu().

[piman, 2014/02/04 22:52:54]

Note: BrowserCompositorOutputSurface doesn't derive from
CompositorOutputSurface, so there's no conflict or anything.

"View" in the renderer context usually refers to RenderView or WebView, which is
mostly unrelated to the OutputSurface, so it's weird. We usually name message
handlers after the messages they handle. If you really feel like you need to
rename this, FromBrowser would carry clearer information than FromView.

     IPC_MESSAGE_HANDLER(ViewMsg_SwapCompositorFrameAck, OnSwapAck);
     IPC_MESSAGE_HANDLER(ViewMsg_ReclaimCompositorResources, OnReclaimResources);
 #if defined(OS_ANDROID)
@@ -147,10 +148,10 @@ void CompositorOutputSurface::OnMessageReceived(const IPC::Message& message) {
   IPC_END_MESSAGE_MAP()
 }
 
-void CompositorOutputSurface::OnUpdateVSyncParameters(
+void CompositorOutputSurface::OnUpdateVSyncParametersFromView(
     base::TimeTicks timebase, base::TimeDelta interval) {
   DCHECK(CalledOnValidThread());
-  OnVSyncParametersChanged(timebase, interval);
+  CommitVSyncParameters(timebase, interval);
 }
 
 #if defined(OS_ANDROID)