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

cc/blink/web_layer_impl.h

 // Copyright 2014 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_BLINK_WEB_LAYER_IMPL_H_
 #define CC_BLINK_WEB_LAYER_IMPL_H_
 
 #include <string>
 
 #include "base/memory/ref_counted.h"
@@ skipping 13 matching lines @@
 #include "third_party/WebKit/public/platform/WebVector.h"
 #include "third_party/skia/include/utils/SkMatrix44.h"
 
 namespace blink {
 class WebFilterOperations;
 class WebLayerClient;
 struct WebFloatRect;
 }
 
 namespace base {
-namespace debug {
+namespace trace_event {
 class ConvertableToTraceFormat;
 }
+
+// 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::ConvertableToTraceFormat;
 }
+}  // namespace base
 
 namespace cc {
 class Layer;
 }
 
 namespace cc_blink {
 
 class WebToCCAnimationDelegateAdapter;
 
 class WebLayerImpl : public blink::WebLayer, public cc::LayerClient {
@@ skipping 98 matching lines @@
 
  private:
   scoped_ptr<WebToCCAnimationDelegateAdapter> animation_delegate_adapter_;
 
   DISALLOW_COPY_AND_ASSIGN(WebLayerImpl);
 };
 
 }  // namespace cc_blink
 
 #endif  // CC_BLINK_WEB_LAYER_IMPL_H_