Add builders for tracing event's structural arguments

cc/output/begin_frame_args.h

Index: cc/output/begin_frame_args.h
diff --git a/cc/output/begin_frame_args.h b/cc/output/begin_frame_args.h
index 91ad182ce0b3aec8c11fe7b750bb5595f4cf86b3..b23a81e183a2180a90684cf92736d59ba3ba5804 100644
--- a/cc/output/begin_frame_args.h
+++ b/cc/output/begin_frame_args.h
@@ -5,10 +5,18 @@
 #ifndef CC_OUTPUT_BEGIN_FRAME_ARGS_H_
 #define CC_OUTPUT_BEGIN_FRAME_ARGS_H_
 
+#include "base/memory/ref_counted.h"
 #include "base/time/time.h"
 #include "base/values.h"
 #include "cc/base/cc_export.h"
 
+namespace base {
+namespace debug {
+class ConvertableToTraceFormat;
+class TracedValue;
+}
+}
+
 namespace cc {
 
 struct CC_EXPORT BeginFrameArgs {
@@ -39,7 +47,8 @@ struct CC_EXPORT BeginFrameArgs {
 
   bool IsValid() const { return interval >= base::TimeDelta(); }
 
-  scoped_ptr<base::Value> AsValue() const;
+  scoped_refptr<base::debug::ConvertableToTraceFormat> AsValue() const;
+  void AsValueInto(base::debug::TracedValue* dict) const;
 
   base::TimeTicks frame_time;
   base::TimeTicks deadline;