gl: Disable SGI_video_sync by default.

ui/gfx/vsync_provider.h

Index: ui/gfx/vsync_provider.h
diff --git a/ui/gfx/vsync_provider.h b/ui/gfx/vsync_provider.h
index 90464bcbf6841ec89840fcca970756338ff39b21..59c7b70134e7731b646ff7b0fc652611b3b543d0 100644
--- a/ui/gfx/vsync_provider.h
+++ b/ui/gfx/vsync_provider.h
@@ -28,6 +28,22 @@ class GFX_EXPORT VSyncProvider {
   virtual void GetVSyncParameters(const UpdateVSyncCallback& callback) = 0;
 };
 
+// Provides a contant timebase and interval.
+class GFX_EXPORT VSyncProviderStub : public VSyncProvider {

[danakj, 2016/08/24 22:20:50]

nit: FixedVsyncProvider or something? Stub implies it does nothing at all IMO.

[brianderson, 2016/08/24 23:51:19]

Will change the name.

[sunnyps, 2016/08/25 01:59:29]

Do we even need a stub vsync provider? Having no vsync provider also works - we
rely on the value of BeginFrameArgs::DefaultInterval in that case.

+ public:
+  VSyncProviderStub(base::TimeTicks timebase, base::TimeDelta interval)
+    : timebase_(timebase), interval_(interval) {
+  }
+
+  ~VSyncProviderStub() override {}
+
+  void GetVSyncParameters(const UpdateVSyncCallback& callback) override;
+
+ private:
+  base::TimeTicks timebase_;
+  base::TimeDelta interval_;
+};
+
 }  // namespace gfx
 
 #endif  // UI_GFX_VSYNC_PROVIDER_H_