Send vsync timebase updates to the browser compositor

cc/layer_tree_host_impl.cc

Index: cc/layer_tree_host_impl.cc
diff --git a/cc/layer_tree_host_impl.cc b/cc/layer_tree_host_impl.cc
index 7c23e0ac64e4711192bc3c62ad80789ac3df3a23..8c4dbb65a8ffa4f43918c151bbea216ee486300c 100644
--- a/cc/layer_tree_host_impl.cc
+++ b/cc/layer_tree_host_impl.cc
@@ -745,6 +745,17 @@ void CCLayerTreeHostImpl::onSwapBuffersComplete()
     m_client->onSwapBuffersCompleteOnImplThread();
 }
 
+void CCLayerTreeHostImpl::onUpdateVSyncTime(int64 time)
+{
+    // TODO(ajuma): Instead of assuming a constant 60 fps, we should adjust when
+    // we clock down.
+    const double intervalInSeconds = 0.01667;
+
+    m_client->onVSyncParametersChanged(
+        time/((double) base::Time::kMicrosecondsPerSecond),
+        intervalInSeconds);
+}
+
 void CCLayerTreeHostImpl::readback(void* pixels, const IntRect& rect)
 {
     ASSERT(m_renderer);