Revert 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 d9395cdb5f729d0c3c1e407a68dd81f697067bbf..61ca35863f44b42f804845780d5d9c22e0256961 100644
--- a/cc/quads/draw_quad.h
+++ b/cc/quads/draw_quad.h
@@ -11,18 +11,12 @@
 #include "cc/resources/resource_provider.h"
 
 namespace base {
-namespace trace_event {
+namespace debug {
 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 {