Add layer name into frame viewer

cc/layers/layer.cc

Index: cc/layers/layer.cc
diff --git a/cc/layers/layer.cc b/cc/layers/layer.cc
index bdcbc755d15db112782d34e3623ca2b07bd58c53..eb48becbd26d53623acb6f535bd27527961ec26e 100644
--- a/cc/layers/layer.cc
+++ b/cc/layers/layer.cc
@@ -6,6 +6,7 @@
 
 #include <algorithm>
 
+#include "base/debug/trace_event.h"
 #include "base/location.h"
 #include "base/metrics/histogram.h"
 #include "base/single_thread_task_runner.h"
@@ -675,7 +676,15 @@ void Layer::PushPropertiesTo(LayerImpl* layer) {
   layer->SetBounds(paint_properties_.bounds);
   layer->SetContentBounds(content_bounds());
   layer->SetContentsScale(contents_scale_x(), contents_scale_y());
-  layer->SetDebugName(debug_name_);
+
+  bool pulling_debug_name;
+  TRACE_EVENT_CATEGORY_GROUP_ENABLED(TRACE_DISABLED_BY_DEFAULT("cc.debug"),

[enne (OOO), 2013/07/09 20:15:32]

Please remove the disabled by default here.

Also, as it turns out, this is calling into Blink code from the compositor
thread while the main thread is blocked.  I think this would be safer to update
the name on the layer during the Update call, which does happen on the main
thread.

[qiankun, 2013/07/10 04:53:07]

Done.
Pull name then call SetDebugName() in ContentLayer::Update()? If it's correct, I
can do this.

[enne (OOO), 2013/07/10 16:48:42]

Yeah, that's exactly it.  Rather than pulling the name in PushPropertiesTo, do
it in Update.

[qiankun, 2013/07/11 10:04:43]

Done.

+                                     &pulling_debug_name);
+  if (pulling_debug_name)
+    layer->SetDebugName(DebugName());
+  else
+    layer->SetDebugName(debug_name_);

[enne (OOO), 2013/07/09 20:15:32]

What about clearing the name if tracing is off?

[qiankun, 2013/07/10 04:53:07]

Ok.

+
   layer->SetCompositingReasons(compositing_reasons_);
   layer->SetDoubleSided(double_sided_);
   layer->SetDrawCheckerboardForMissingTiles(