cc: Add main frame timing info to frame timing tracker.

cc/trees/layer_tree_impl.cc

Index: cc/trees/layer_tree_impl.cc
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index b5f8aed2307ba159c5c091f123706c768324942f..c2edaae65d308c7b3eca5b5b5607288d99012da5 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -34,7 +34,6 @@
 #include "ui/gfx/geometry/vector2d_conversions.h"
 
 namespace cc {
-
 // This class exists to split the LayerScrollOffsetDelegate between the
 // InnerViewportScrollLayer and the OuterViewportScrollLayer in a manner
 // that never requires the embedder or LayerImpl to know about.
@@ -135,6 +134,20 @@ void LayerTreeImpl::RecreateResources() {
   }
 }
 
+void LayerTreeImpl::GatherFrameTimingRequestIds(
+    std::vector<int64_t>* request_ids) {
+  if (!root_layer_)
+    return;
+
+  // TODO(vmpstr): Early out if there are no requests on any of the layers. For
+  // that, we need to inform LayerTreeImpl whenever there are requests when we
+  // get them.
+  LayerTreeHostCommon::CallFunctionForSubtree(
+      root_layer_.get(), [request_ids](LayerImpl* layer) {
+        layer->GatherFrameTimingRequestIds(request_ids);
+      });
+}
+
 void LayerTreeImpl::SetRootLayer(scoped_ptr<LayerImpl> layer) {
   if (inner_viewport_scroll_layer_)
     inner_viewport_scroll_layer_->SetScrollOffsetDelegate(NULL);