CC: Force push properties for all layers when tracing is started

cc/trees/layer_tree_host.cc

Index: cc/trees/layer_tree_host.cc
diff --git a/cc/trees/layer_tree_host.cc b/cc/trees/layer_tree_host.cc
index 2ac7ebe5b413b97a3b82e1f3cffb58d0e5a213ce..ea9cd0bdaa6e5bdf6c8dc0ad9dec3ddc969e5a7c 100644
--- a/cc/trees/layer_tree_host.cc
+++ b/cc/trees/layer_tree_host.cc
@@ -21,6 +21,7 @@
 #include "cc/animation/layer_animation_controller.h"
 #include "cc/base/math_util.h"
 #include "cc/debug/devtools_instrumentation.h"
+#include "cc/debug/frame_viewer_instrumentation.h"
 #include "cc/debug/rendering_stats_instrumentation.h"
 #include "cc/input/layer_selection_bound.h"
 #include "cc/input/page_scale_animation.h"
@@ -294,6 +295,14 @@ void LayerTreeHost::FinishCommitOnImplThread(LayerTreeHostImpl* host_impl) {
 
   sync_tree->set_source_frame_number(source_frame_number());
 
+  bool is_new_trace;

[danakj, 2015/03/16 19:06:49]

Can you move this up above the |sync_tree| variable? It's kinda in the middle of
"update the sync tree" here

+  TRACE_EVENT_IS_NEW_TRACE(&is_new_trace);
+  if (is_new_trace &&
+      frame_viewer_instrumentation::IsTracingLayerTreeSnapshots()) {
+    LayerTreeHostCommon::CallFunctionForSubtree(
+        root_layer(), [](Layer* layer) { layer->DidBeginTracing(); });
+  }
+
   if (needs_full_tree_sync_) {
     sync_tree->SetRootLayer(TreeSynchronizer::SynchronizeTrees(
         root_layer(), sync_tree->DetachLayerTree(), sync_tree));