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

cc/base/math_util.h

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_BASE_MATH_UTIL_H_
 #define CC_BASE_MATH_UTIL_H_
 
 #include <algorithm>
 #include <cmath>
 #include <vector>
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/cc_export.h"
 #include "ui/gfx/geometry/box_f.h"
 #include "ui/gfx/geometry/point3_f.h"
 #include "ui/gfx/geometry/point_f.h"
 #include "ui/gfx/geometry/scroll_offset.h"
 #include "ui/gfx/geometry/size.h"
 #include "ui/gfx/transform.h"
 
 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;
 class Rect;
 class RectF;
 class Transform;
 class Vector2dF;
 class Vector2d;
 }
 
@@ skipping 200 matching lines @@
 
   // Returns a base::Value representation of the floating point value.
   // If the value is inf, returns max double/float representation.
   static double AsDoubleSafely(double value);
   static float AsFloatSafely(float value);
 };
 
 }  // namespace cc
 
 #endif  // CC_BASE_MATH_UTIL_H_