Moves some files into mojo/common

mojo/shell/handle_watcher.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 MOJO_SHELL_HANDLE_WATCHER_H_
-#define MOJO_SHELL_HANDLE_WATCHER_H_
-
-#include "base/basictypes.h"
-#include "base/callback_forward.h"
-#include "base/memory/scoped_ptr.h"
-#include "mojo/public/system/core.h"
-
-namespace base {
-class Thread;
-class TickClock;
-class TimeTicks;
-}
-
-namespace mojo {
-namespace shell {
-namespace test {
-class HandleWatcherTest;
-}
-
-// HandleWatcher is used to asynchronously wait on a handle and notify a Closure
-// when the handle is ready, or the deadline has expired.
-class HandleWatcher {
- public:
-  HandleWatcher();
-  ~HandleWatcher();
-
-  // Starts listening for |handle|. This implicitly invokes Stop(). In other
-  // words, Start() performs one asynchronous watch at a time. It is ok to call
-  // Start() multiple times, but it cancels any existing watches. |callback| is
-  // notified when the handle is ready, invalid or deadline has passed and is
-  // notified on the thread Start() was invoked on.
-  void Start(MojoHandle handle,
-             MojoWaitFlags wait_flags,
-             MojoDeadline deadline,
-             const base::Closure& callback);
-
-  // Stops listening. Does nothing if not in the process of listening.
-  void Stop();
-
-  // Returns now. Used internally; generally not useful.
-  static base::TimeTicks NowTicks();
-
-  // Converts a MojoDeadline into a TimeTicks.
-  static base::TimeTicks MojoDeadlineToTimeTicks(MojoDeadline deadline);
-
- private:
-  friend class test::HandleWatcherTest;
-  struct StartState;
-
-  // See description of |StartState::weak_factory| for details.
-  void OnHandleReady();
-
-  // If non-NULL Start() has been invoked.
-  scoped_ptr<StartState> start_state_;
-
-  // Used for getting the time. Only set by tests.
-  static base::TickClock* tick_clock_;
-
-  DISALLOW_COPY_AND_ASSIGN(HandleWatcher);
-};
-
-}  // namespace shell
-}  // namespace mojo
-
-#endif  // MOJO_SHELL_HANDLE_WATCHER_H_