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

content/child/child_thread_impl.h

 // Copyright (c) 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 CONTENT_CHILD_CHILD_THREAD_IMPL_H_
 #define CONTENT_CHILD_CHILD_THREAD_IMPL_H_
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/shared_memory.h"
 #include "base/memory/weak_ptr.h"
 #include "base/power_monitor/power_monitor.h"
 #include "base/tracked_objects.h"
 #include "content/child/mojo/mojo_application.h"
 #include "content/common/content_export.h"
 #include "content/common/message_router.h"
 #include "content/public/child/child_thread.h"
 #include "ipc/ipc_message.h"  // For IPC_MESSAGE_LOG_ENABLED.
 
 namespace base {
 class MessageLoop;
 
-namespace trace_event {
+namespace debug {
 class TraceMemoryController;
-}  // namespace trace_event
-
-// 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::TraceMemoryController;
 }  // namespace debug
 }  // namespace base
 
 namespace IPC {
 class MessageFilter;
 class SyncChannel;
 class SyncMessageFilter;
 }  // namespace IPC
 
 namespace blink {
@@ skipping 264 matching lines @@
   bool in_browser_process_;
 
   base::WeakPtrFactory<ChildThreadImpl> channel_connected_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ChildThreadImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_CHILD_THREAD_IMPL_H_