cc: add more devtools instrumentation

cc/trees/thread_proxy.h

Index: cc/trees/thread_proxy.h
diff --git a/cc/trees/thread_proxy.h b/cc/trees/thread_proxy.h
index dadd2b4800c8fdffbb1072a57fc84e604f0ba24f..76d18f58d135cc78cca6dc5490f3f61603b2b72f 100644
--- a/cc/trees/thread_proxy.h
+++ b/cc/trees/thread_proxy.h
@@ -167,8 +167,7 @@ class ThreadProxy : public Proxy,
   void BeginMainFrameAbortedOnImplThread(bool did_handle);
   void RequestReadbackOnImplThread(ReadbackRequest* request);
   void FinishAllRenderingOnImplThread(CompletionEvent* completion);
-  void InitializeImplOnImplThread(CompletionEvent* completion,
-                                  int layer_tree_host_id);
+  void InitializeImplOnImplThread(CompletionEvent* completion);
   void SetLayerTreeHostClientReadyOnImplThread();
   void SetVisibleOnImplThread(CompletionEvent* completion, bool visible);
   void UpdateBackgroundAnimateTicking();
@@ -253,9 +252,11 @@ class ThreadProxy : public Proxy,
   const MainThreadOrBlockedMainThread& blocked_main() const;
 
   struct CompositorThreadOnly {
-    explicit CompositorThreadOnly(ThreadProxy* proxy);
+    CompositorThreadOnly(ThreadProxy* proxy, int layer_tree_host_id);
     ~CompositorThreadOnly();
 
+    const int layer_tree_host_id;
+
     // Copy of the main thread side contents texture manager for work
     // that needs to be done on the compositor thread.
     PrioritizedResourceManager* contents_texture_manager;