Update from https://crrev.com/315085

base/win/object_watcher.h

 // Copyright (c) 2011 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 BASE_WIN_OBJECT_WATCHER_H_
 #define BASE_WIN_OBJECT_WATCHER_H_
 
 #include <windows.h>
 
 #include "base/base_export.h"
@@ skipping 56 matching lines @@
   bool StartWatching(HANDLE object, Delegate* delegate);
 
   // Stops watching.  Does nothing if the watch has already completed.  If the
   // watch is still active, then it is canceled, and the associated delegate is
   // not notified.
   //
   // Returns true if the watch was canceled.  Otherwise, false is returned.
   //
   bool StopWatching();
 
-  // Returns the handle of the object being watched, or NULL if the object
-  // watcher is stopped.
-  HANDLE GetWatchedObject();
+  // Returns true if currently watching an object.
+  bool IsWatching() const;
+
+  // Returns the handle of the object being watched.
+  HANDLE GetWatchedObject() const;
 
  private:
   // Called on a background thread when done waiting.
   static void CALLBACK DoneWaiting(void* param, BOOLEAN timed_out);
 
   void Signal(Delegate* delegate);
 
   // MessageLoop::DestructionObserver implementation:
   virtual void WillDestroyCurrentMessageLoop();
 
   // Internal state.
   Closure callback_;
   HANDLE object_;             // The object being watched
   HANDLE wait_object_;        // Returned by RegisterWaitForSingleObject
   MessageLoop* origin_loop_;  // Used to get back to the origin thread
 
   WeakPtrFactory<ObjectWatcher> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ObjectWatcher);
 };
 
 }  // namespace win
 }  // namespace base
 
 #endif  // BASE_OBJECT_WATCHER_H_