Read compositor VSync information from platform, when possible

The current query of VSync information through the GL context can be unreliable
on platforms that can dynamically disable vblanks, or multi-monitor setups.
Preferentially query the VSync information through the platform windowing
system (presently: XRandR on CrOS) when possible.

BUG=328953
TEST=local build, run on CrOS snow

Review URL: https://codereview.chromium.org/138903025

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250250 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 14 insertions, 11 deletions

diff --git a/cc/output/output_surface.cc b/cc/output/output_surface.cc
index 9ba6dbb..87d6e84 100644
--- a/cc/output/output_surface.cc
+++ b/cc/output/output_surface.cc
@@ -117,11 +117,14 @@ void OutputSurface::SetMaxFramesPending(int max_frames_pending) {
   max_frames_pending_ = max_frames_pending;
 }
 
-void OutputSurface::OnVSyncParametersChanged(base::TimeTicks timebase,
-                                             base::TimeDelta interval) {
-  TRACE_EVENT2("cc", "OutputSurface::OnVSyncParametersChanged",
-               "timebase", (timebase - base::TimeTicks()).InSecondsF(),
-               "interval", interval.InSecondsF());
+void OutputSurface::CommitVSyncParameters(base::TimeTicks timebase,
+                                          base::TimeDelta interval) {
+  TRACE_EVENT2("cc",
+               "OutputSurface::CommitVSyncParameters",
+               "timebase",
+               (timebase - base::TimeTicks()).InSecondsF(),
+               "interval",
+               interval.InSecondsF());
   if (frame_rate_controller_)
     frame_rate_controller_->SetTimebaseAndInterval(timebase, interval);
 }
diff --git a/cc/output/output_surface.h b/cc/output/output_surface.h
index 4478754..b751f06 100644
--- a/cc/output/output_surface.h
+++ b/cc/output/output_surface.h
@@ -159,8 +159,8 @@ class CC_EXPORT OutputSurface : public FrameRateControllerClient {
 
   // The FrameRateController is deprecated.
   // Platforms should move to native BeginImplFrames instead.
-  void OnVSyncParametersChanged(base::TimeTicks timebase,
-                                base::TimeDelta interval);
+  void CommitVSyncParameters(base::TimeTicks timebase,
+                             base::TimeDelta interval);
   virtual void FrameRateControllerTick(bool throttled,
                                        const BeginFrameArgs& args) OVERRIDE;
   scoped_ptr<FrameRateController> frame_rate_controller_;
diff --git a/cc/output/output_surface_unittest.cc b/cc/output/output_surface_unittest.cc
index 73a76a3..b0220fb 100644
--- a/cc/output/output_surface_unittest.cc
+++ b/cc/output/output_surface_unittest.cc
@@ -46,9 +46,9 @@ class TestOutputSurface : public OutputSurface {
 
   using OutputSurface::ReleaseGL;
 
-  void OnVSyncParametersChangedForTesting(base::TimeTicks timebase,
-                                          base::TimeDelta interval) {
-    OnVSyncParametersChanged(timebase, interval);
+  void CommitVSyncParametersForTesting(base::TimeTicks timebase,
+                                       base::TimeDelta interval) {
+    CommitVSyncParameters(timebase, interval);
   }
 
   void BeginImplFrameForTesting() {
@@ -387,7 +387,7 @@ TEST(OutputSurfaceTest,
 
   // We need to subtract an epsilon from Now() because some platforms have
   // a slow clock.
-  output_surface.OnVSyncParametersChangedForTesting(
+  output_surface.CommitVSyncParametersForTesting(
       gfx::FrameTime::Now() - base::TimeDelta::FromSeconds(1), big_interval);
 
   output_surface.SetMaxFramesPending(2);