Implement DeviceMotionEvent API

chromeos/accelerometer/accelerometer_reader.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 CHROMEOS_ACCELEROMETER_ACCELEROMETER_READER_H_
 #define CHROMEOS_ACCELEROMETER_ACCELEROMETER_READER_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
@@ skipping 45 matching lines @@
     virtual ~Observer() {}
   };
 
   static AccelerometerReader* GetInstance();
 
   void Initialize(scoped_refptr<base::TaskRunner> blocking_task_runner);
 
   // Add/Remove observers.
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
+  bool HasObserver(Observer* observer);
 
  protected:
   AccelerometerReader();
   virtual ~AccelerometerReader();
 
  private:
   friend struct DefaultSingletonTraits<AccelerometerReader>;
 
   // Dispatched when initialization is complete. If |success|, |configuration|
   // provides the details of the detected accelerometer.
@@ skipping 23 matching lines @@
   ObserverList<Observer, true> observers_;
 
   base::WeakPtrFactory<AccelerometerReader> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AccelerometerReader);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_ACCELEROMETER_ACCELEROMETER_READER_H_