Add builders for tracing event's structural arguments

cc/trees/proxy.h

Index: cc/trees/proxy.h
diff --git a/cc/trees/proxy.h b/cc/trees/proxy.h
index 7854edc7e07e58ab1cccc5013ede718562274ee7..6100562f444c51a13ded9ca59bf76e69db1ace17 100644
--- a/cc/trees/proxy.h
+++ b/cc/trees/proxy.h
@@ -16,7 +16,12 @@
 #include "base/values.h"
 #include "cc/base/cc_export.h"
 
-namespace base { class SingleThreadTaskRunner; }
+namespace base {
+namespace debug {
+class TracedValue;
+}
+class SingleThreadTaskRunner;
+}
 
 namespace gfx {
 class Rect;
@@ -91,13 +96,12 @@ class CC_EXPORT Proxy {
 
   virtual bool SupportsImplScrolling() const = 0;
 
-  virtual scoped_ptr<base::Value> AsValue() const = 0;
+  virtual void AsValueInto(base::debug::TracedValue* value) const = 0;
 
   virtual void SetDebugState(const LayerTreeDebugState& debug_state) = 0;
 
   // Testing hooks
   virtual bool CommitPendingForTesting() = 0;
-  virtual scoped_ptr<base::Value> SchedulerAsValueForTesting();
 
  protected:
   Proxy(scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,