Read compositor VSync information from platform, when possible

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index 599f976566f37beacdcc3adfd01e3d9e2cf174ec..a46c45cebcf81e448c8a34cf51403aed5745ac19 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -3204,7 +3204,6 @@ void RenderWidgetHostViewAura::OnCompositingLockStateChanged(
 }
 
 void RenderWidgetHostViewAura::OnUpdateVSyncParameters(
-    ui::Compositor* compositor,
     base::TimeTicks timebase,
     base::TimeDelta interval) {
   if (IsShowing()) {
@@ -3499,6 +3498,10 @@ void RenderWidgetHostViewAura::AddedToRootWindow() {
     if (input_method)
       input_method->SetFocusedTextInputClient(this);
   }
+
+  ui::Compositor* compositor = GetCompositor();
+  if (compositor)
+    compositor->vsync_manager()->AddObserver(this);
 }
 
 void RenderWidgetHostViewAura::RemovingFromRootWindow() {
@@ -3523,8 +3526,11 @@ void RenderWidgetHostViewAura::RemovingFromRootWindow() {
   RunOnCommitCallbacks();
   resize_lock_.reset();
   host_->WasResized();
-  if (compositor && compositor->HasObserver(this))
-    compositor->RemoveObserver(this);
+  if (compositor) {
+    if (compositor->HasObserver(this))
+      compositor->RemoveObserver(this);
+    compositor->vsync_manager()->RemoveObserver(this);
+  }
 }
 
 ui::Compositor* RenderWidgetHostViewAura::GetCompositor() const {