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..3bcb6eb9a513d87df2d7d222537b445401b68c33 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"
 
@@ -50,7 +50,8 @@ class CHROMEOS_EXPORT AccelerometerReader {
   // An interface to receive data from the AccelerometerReader.
   class Observer {
    public:
-    virtual void OnAccelerometerUpdated(const AccelerometerUpdate& update) = 0;
+    virtual void OnAccelerometerUpdated(
+        scoped_refptr<const AccelerometerUpdate> update) = 0;
 
    protected:
     virtual ~Observer() {}
@@ -63,6 +64,10 @@ class CHROMEOS_EXPORT AccelerometerReader {
   // Add/Remove observers.
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
+  bool HasObserver(Observer* observer);
+
+  // The delay between reads of the accelerometer.
+  int DelayBetweenReadsMs() const;

[flackr, 2015/03/05 19:59:45]

Until we resolve increasing the update rate, I think we should just expose the
constant in the header like this:
https://code.google.com/p/chromium/codesearch#chromium/src/ash/wm/overview/wi...

[jonross, 2015/03/05 21:13:39]

Done.

 
  protected:
   AccelerometerReader();
@@ -88,15 +93,12 @@ class CHROMEOS_EXPORT AccelerometerReader {
   scoped_refptr<base::TaskRunner> task_runner_;
 
   // The last seen accelerometer data.
-  AccelerometerUpdate update_;
-
-  // True if a valid accelerometer update is available.
-  bool has_update_;
+  scoped_refptr<AccelerometerUpdate> update_;
 
   // The accelerometer configuration.
   scoped_refptr<Configuration> configuration_;
 
-  ObserverList<Observer, true> observers_;
+  scoped_refptr<ObserverListThreadSafe<Observer>> observers_;
 
   base::WeakPtrFactory<AccelerometerReader> weak_factory_;