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

cc/output/filter_operations.h

 // Copyright 2013 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_OUTPUT_FILTER_OPERATIONS_H_
 #define CC_OUTPUT_FILTER_OPERATIONS_H_
 
 #include <vector>
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "cc/output/filter_operation.h"
 
 namespace base {
-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;
+}
 class Value;
-}
+}  // namespace base
 
 namespace cc {
 
 // An ordered list of filter operations.
 class CC_EXPORT FilterOperations {
  public:
   FilterOperations();
 
   FilterOperations(const FilterOperations& other);
 
@@ skipping 42 matching lines @@
 
   void AsValueInto(base::debug::TracedValue* value) const;
 
  private:
   std::vector<FilterOperation> operations_;
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_FILTER_OPERATIONS_H_