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

cc/resources/picture_layer_tiling_set.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_RESOURCES_PICTURE_LAYER_TILING_SET_H_
 #define CC_RESOURCES_PICTURE_LAYER_TILING_SET_H_
 
 #include <set>
 #include <vector>
 
 #include "cc/base/region.h"
 #include "cc/base/scoped_ptr_vector.h"
 #include "cc/resources/picture_layer_tiling.h"
 #include "ui/gfx/geometry/size.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;
 }
-}  // namespace base
 
 namespace cc {
 
 class CC_EXPORT PictureLayerTilingSet {
  public:
   enum TilingRangeType {
     HIGHER_THAN_HIGH_RES,
     HIGH_RES,
     BETWEEN_HIGH_AND_LOW_RES,
     LOW_RES,
@@ skipping 142 matching lines @@
   const int skewport_extrapolation_limit_in_content_pixels_;
   PictureLayerTilingClient* client_;
 
   friend class Iterator;
   DISALLOW_COPY_AND_ASSIGN(PictureLayerTilingSet);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_PICTURE_LAYER_TILING_SET_H_