Put code in //services/js in namespace js

services/js/js_app_message_loop_observers.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 SERVICES_JS_JS_APP_MESSAGE_LOOP_OBSERVERS_H_
 #define SERVICES_JS_JS_APP_MESSAGE_LOOP_OBSERVERS_H_
 
 #include "base/message_loop/message_loop.h"
 #include "mojo/common/message_pump_mojo.h"
 #include "v8/include/v8.h"
 
-namespace mojo {
 namespace js {
 
 class JSAppMessageLoopObservers {
  public:
   explicit JSAppMessageLoopObservers(v8::Isolate* isolate);
   ~JSAppMessageLoopObservers();
 
  private:
   class TaskObserver : public base::MessageLoop::TaskObserver {
    public:
     explicit TaskObserver(JSAppMessageLoopObservers* loop_observers);
     void WillProcessTask(const base::PendingTask& pending_task) override;
     void DidProcessTask(const base::PendingTask& pending_task) override;
    private:
     JSAppMessageLoopObservers* loop_observers_;
   };
 
-  class SignalObserver : public common::MessagePumpMojo::Observer {
+  class SignalObserver : public mojo::common::MessagePumpMojo::Observer {
    public:
     explicit SignalObserver(JSAppMessageLoopObservers* loop_observers);
     void WillSignalHandler() override;
     void DidSignalHandler() override;
   private:
     JSAppMessageLoopObservers* loop_observers_;
   };
 
   void RunMicrotasks();
 
   v8::Isolate* isolate_;
   TaskObserver task_observer_;
   SignalObserver signal_observer_;
 };
 
 }  // namespace js
-}  // namespace mojo
 
 #endif  // SERVICES_JS_JS_APP_MESSAGE_LOOP_OBSERVERS_H_