Implement DeviceMotionEvent API

chromeos/accelerometer/accelerometer_reader.h

Index: chromeos/accelerometer/accelerometer_reader.h
diff --git a/chromeos/accelerometer/accelerometer_reader.h b/chromeos/accelerometer/accelerometer_reader.h
index cca75050eced76d6b92411979732b51301961f4f..bca5b5e1f2ccb6276b7618585a7ec04a751a783a 100644
--- a/chromeos/accelerometer/accelerometer_reader.h
+++ b/chromeos/accelerometer/accelerometer_reader.h
@@ -7,7 +7,7 @@
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
-#include "base/observer_list.h"
+#include "base/observer_list_threadsafe.h"
 #include "chromeos/accelerometer/accelerometer_types.h"
 #include "chromeos/chromeos_export.h"
 
@@ -63,6 +63,7 @@ class CHROMEOS_EXPORT AccelerometerReader {
   // Add/Remove observers.
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
+  bool HasObserver(Observer* observer);
 
  protected:
   AccelerometerReader();
@@ -96,7 +97,7 @@ class CHROMEOS_EXPORT AccelerometerReader {
   // The accelerometer configuration.
   scoped_refptr<Configuration> configuration_;
 
-  ObserverList<Observer, true> observers_;
+  scoped_refptr<ObserverListThreadSafe<Observer>> observers_;
 
   base::WeakPtrFactory<AccelerometerReader> weak_factory_;