Update from https://crrev.com/315085

cc/base/math_util.h

Index: cc/base/math_util.h
diff --git a/cc/base/math_util.h b/cc/base/math_util.h
index d9cc43b552eb1042381569f0ff377a1d3de865d0..ddc8955255870d8379df1771a823394cd3400b54 100644
--- a/cc/base/math_util.h
+++ b/cc/base/math_util.h
@@ -21,10 +21,16 @@
 
 namespace base {
 class Value;
-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;
 }
+}  // namespace base
 
 namespace gfx {
 class QuadF;