Cherry pick "Add source frame number to LayerTreeImpl::AsValueInto"

Add source frame number to LayerTreeImpl::AsValueInto

Will help work around
https://code.google.com/p/trace-viewer/issues/detail?id=587

R=enne

Review URL: https://codereview.chromium.org/495423003

Cr-Commit-Position: refs/heads/master@{#291573}

Chromium change: 929378a002b5756a9f8501e292c157ecedfa36bb
Bug: 17315710

Change-Id: Ia409efc82e1d5d011906846c0c3304e0f36c4987
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index 6bcc9fc..2988e14 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -794,6 +794,7 @@
   scoped_ptr<base::DictionaryValue> state(new base::DictionaryValue());
   TracedValue::MakeDictIntoImplicitSnapshot(
       state.get(), "cc::LayerTreeImpl", this);
+  state->SetInteger("source_frame_number", source_frame_number_);
 
   state->Set("root_layer", root_layer_->AsValue().release());