Reland of Move tracing namespace from base::debug to base::trace_event.

cc/quads/draw_quad.h

Index: cc/quads/draw_quad.h
diff --git a/cc/quads/draw_quad.h b/cc/quads/draw_quad.h
index 61ca35863f44b42f804845780d5d9c22e0256961..d9395cdb5f729d0c3c1e407a68dd81f697067bbf 100644
--- a/cc/quads/draw_quad.h
+++ b/cc/quads/draw_quad.h
@@ -11,12 +11,18 @@
 #include "cc/resources/resource_provider.h"
 
 namespace base {
-namespace debug {
+namespace trace_event {
 class TracedValue;
 }
+
+// TODO(ssid): remove these aliases after the tracing clients are moved to the
+// new trace_event namespace. See crbug.com/451032. ETA: March 2015
+namespace debug {
+using ::base::trace_event::TracedValue;
+}
 class Value;
 class DictionaryValue;
-}
+}  // namespace base
 
 namespace cc {