cc: add DevTools instrumentation for impl-side frames

cc/debug/devtools_instrumentation.h

Index: cc/debug/devtools_instrumentation.h
diff --git a/cc/debug/devtools_instrumentation.h b/cc/debug/devtools_instrumentation.h
index eea9e62f02aa0881e0e9ae1ee7a909f9c139f198..9d01599c8a345b87ae222bb8e792ca604f501d9b 100644
--- a/cc/debug/devtools_instrumentation.h
+++ b/cc/debug/devtools_instrumentation.h
@@ -12,12 +12,15 @@ namespace devtools_instrumentation {
 
 namespace internal {
 const char kCategory[] = "cc,devtools";
+const char kFrameId[] = "frameId";
 const char kLayerId[] = "layerId";
 const char kLayerTreeId[] = "layerTreeId";
 const char kPixelRefId[] = "pixelRefId";
 
 const char kImageDecodeTask[] = "ImageDecodeTask";
-}
+const char kBeginFrame[] = "BeginFrame";
+const char kCommitMainThreadFrame[] = "CommitMainThreadFrame";
+}  // namespace internal
 
 const char kPaintLayer[] = "PaintLayer";
 const char kRasterTask[] = "RasterTask";
@@ -84,6 +87,21 @@ struct ScopedLayerObjectTracker
   DISALLOW_COPY_AND_ASSIGN(ScopedLayerObjectTracker);
 };
 
+inline void didCommitMainThreadFrame(uint64 tree_id, int frame_id) {

[nduca, 2013/11/06 19:05:12]

remind me what the tree id does?

[caseq, 2013/11/07 06:36:26]

It's actually LTH id -- we use it on the Timeline's side to tell apart LTHs of
different views within the same process, so that we only process events from the
inspected page.

+  TRACE_EVENT_INSTANT2(internal::kCategory,
+                       internal::kCommitMainThreadFrame,
+                       TRACE_EVENT_SCOPE_THREAD,
+                       internal::kLayerTreeId, tree_id,
+                       internal::kFrameId, frame_id);
+}
+
+inline void didBeginFrame(uint64 tree_id) {
+  TRACE_EVENT_INSTANT1(internal::kCategory,
+                       internal::kBeginFrame,
+                       TRACE_EVENT_SCOPE_THREAD,
+                       internal::kLayerTreeId, tree_id);
+}
+
 }  // namespace devtools_instrumentation
 }  // namespace cc