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

content/browser/browser_main_loop.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_BROWSER_BROWSER_MAIN_LOOP_H_
 #define CONTENT_BROWSER_BROWSER_MAIN_LOOP_H_
 
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/timer/timer.h"
 #include "content/browser/browser_process_sub_thread.h"
 #include "content/public/browser/browser_main_runner.h"
 
 namespace base {
 class CommandLine;
 class FilePath;
 class HighResolutionTimerManager;
 class MessageLoop;
 class PowerMonitor;
 class SystemMonitor;
 #if defined(OS_CHROMEOS)
 class MemoryPressureObserverChromeOS;
 #endif
-namespace trace_event {
+namespace debug {
 class TraceMemoryController;
 class TraceEventSystemStatsMonitor;
-}  // 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::TraceEventSystemStatsMonitor;
-using ::base::trace_event::TraceMemoryController;
 }  // namespace debug
 }  // namespace base
 
 namespace media {
 class AudioManager;
 class MidiManager;
 class UserInputMonitor;
 }  // namespace media
 
 namespace net {
@@ skipping 181 matching lines @@
 
   // This timer initiates trace file saving.
   base::OneShotTimer<BrowserMainLoop> startup_trace_timer_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserMainLoop);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_BROWSER_MAIN_LOOP_H_