Send vsync timebase updates to the browser compositor

cc/layer_tree_host_impl.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 
 #include "CCLayerTreeHostImpl.h"
 
 #include "base/basictypes.h"
 #include "CCAppendQuadsData.h"
@@ skipping 727 matching lines @@
 void CCLayerTreeHostImpl::didLoseContext()
 {
     m_client->didLoseContextOnImplThread();
 }
 
 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);
     m_renderer->getFramebufferPixels(pixels, rect);
 }
 
 static CCLayerImpl* findRootScrollLayer(CCLayerImpl* layer)
 {
     if (!layer)
         return 0;
@@ skipping 695 matching lines @@
 
     CCScrollbarAnimationController* scrollbarController = layer->scrollbarAnimationController();
     if (scrollbarController && scrollbarController->animate(monotonicTime))
         m_client->setNeedsRedrawOnImplThread();
 
     for (size_t i = 0; i < layer->children().size(); ++i)
         animateScrollbarsRecursive(layer->children()[i], monotonicTime);
 }
 
 }  // namespace cc