Add builders for tracing event's structural arguments

cc/resources/picture_layer_tiling_set.h

Index: cc/resources/picture_layer_tiling_set.h
diff --git a/cc/resources/picture_layer_tiling_set.h b/cc/resources/picture_layer_tiling_set.h
index 6452dde5d15ddcf1c68da23b58ed50aa0db351ce..abef2806fb22430157262b7bc0cd46a7c41b10be 100644
--- a/cc/resources/picture_layer_tiling_set.h
+++ b/cc/resources/picture_layer_tiling_set.h
@@ -10,6 +10,12 @@
 #include "cc/resources/picture_layer_tiling.h"
 #include "ui/gfx/size.h"
 
+namespace base {
+namespace debug {
+class TracedValue;
+}
+}
+
 namespace cc {
 
 class CC_EXPORT PictureLayerTilingSet {
@@ -101,7 +107,7 @@ class CC_EXPORT PictureLayerTilingSet {
     Region::Iterator region_iter_;
   };
 
-  scoped_ptr<base::Value> AsValue() const;
+  void AsValueInto(base::debug::TracedValue* array) const;
   size_t GPUMemoryUsageInBytes() const;
 
  private: