Add builders for tracing event's structural arguments

cc/base/region.cc

Index: cc/base/region.cc
diff --git a/cc/base/region.cc b/cc/base/region.cc
index 906bc6e3c9d1e6f0ccce6445e078015e4754b78a..79c30ec8251a0b0b881aed2ba304bbcc63eb64ba 100644
--- a/cc/base/region.cc
+++ b/cc/base/region.cc
@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 #include "cc/base/region.h"
+#include "base/debug/trace_event_argument.h"
 #include "base/values.h"
 
 namespace cc {
@@ -120,6 +121,16 @@ scoped_ptr<base::Value> Region::AsValue() const {
   return result.PassAs<base::Value>();
 }
 
+void Region::AsValueInto(base::debug::TracedValue* result) const {
+  for (Iterator it(*this); it.has_rect(); it.next()) {
+    gfx::Rect rect(it.rect());
+    result->AppendInteger(rect.x());
+    result->AppendInteger(rect.y());
+    result->AppendInteger(rect.width());
+    result->AppendInteger(rect.height());
+  }
+}
+
 Region::Iterator::Iterator() {
 }