Make HandleWatcher watch on the same thread if the thread is running a MessagePumpMojo.

mojo/public/cpp/application/application_runner_chromium.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 MOJO_PUBLIC_APPLICATION_APPLICATION_RUNNER_CHROMIUM_H_
 #define MOJO_PUBLIC_APPLICATION_APPLICATION_RUNNER_CHROMIUM_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "mojo/public/cpp/system/core.h"
 
 namespace mojo {
 
 class ApplicationDelegate;
 
 // A utility for running a chromium based mojo Application. The typical use
 // case is to use when writing your MojoMain:
 //
 //  MojoResult MojoMain(MojoHandle shell_handle) {
 //    mojo::ApplicationRunnerChromium runner(new MyDelegate());
 //    return runner.Run(shell_handle);
 //  }
 //
 // ApplicationRunnerChromium takes care of chromium environment initialization
-// and shutdown, and starting a RunLoop from which your application can run and
-// ultimately Quit().
+// and shutdown, and starting a MessageLoop from which your application can run
+// and ultimately Quit().
 class ApplicationRunnerChromium {
  public:
   // Takes ownership of |delegate|.
   explicit ApplicationRunnerChromium(ApplicationDelegate* delegate);
   ~ApplicationRunnerChromium();
 
   void set_message_loop_type(base::MessageLoop::Type type);
 
   // Once the various parameters have been set above, use Run to initialize an
-  // ApplicationImpl wired to the provided delegate, and run a RunLoop until
+  // ApplicationImpl wired to the provided delegate, and run a MessageLoop until
   // the application exits.
   MojoResult Run(MojoHandle shell_handle);
 
  private:
   scoped_ptr<ApplicationDelegate> delegate_;
 
-  // MessageLoop type. TYPE_DEFAULT is default.
+  // MessageLoop type. TYPE_CUSTOM is default (MessagePumpMojo will be used as
+  // the underlying message pump).
   base::MessageLoop::Type message_loop_type_;
+  // Whether Run() has been called.
+  bool has_run_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(ApplicationRunnerChromium);
 };
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_APPLICATION_APPLICATION_RUNNER_CHROMIUM_H_