Change AccelerometerReader to a Singleton

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 1d0c6ecebb3e45f6074f6bc488c236424fd3bb40..15115da0d3aa5ce121f0ed9c812281657869605d 100644
--- a/chromeos/accelerometer/accelerometer_reader.h
+++ b/chromeos/accelerometer/accelerometer_reader.h
@@ -11,6 +11,9 @@
 #include "chromeos/chromeos_export.h"
 #include "ui/accelerometer/accelerometer_types.h"
 
+template <typename T>
+struct DefaultSingletonTraits;
+
 namespace base {
 class TaskRunner;
 }
@@ -54,8 +57,7 @@ class CHROMEOS_EXPORT AccelerometerReader {
     virtual ~Observer() {}
   };
 
-  AccelerometerReader();
-  ~AccelerometerReader();
+  static AccelerometerReader* GetInstance();
 
   void Initialize(scoped_refptr<base::TaskRunner> blocking_task_runner);
 
@@ -69,7 +71,13 @@ class CHROMEOS_EXPORT AccelerometerReader {
   static bool IsReadingStable(const ui::AccelerometerUpdate& update,
                               ui::AccelerometerSource source);
 
+ protected:
+  AccelerometerReader();
+  virtual ~AccelerometerReader();
+
  private:
+  friend struct DefaultSingletonTraits<AccelerometerReader>;
+
   // Dispatched when initialization is complete. If |success|, |configuration|
   // provides the details of the detected accelerometer.
   void OnInitialized(scoped_refptr<Configuration> configuration, bool success);