Implement PollingThread for Device Motion.

content/browser/device_orientation/data_fetcher_shared_memory.h

Index: content/browser/device_orientation/data_fetcher_shared_memory.h
diff --git a/content/browser/device_orientation/data_fetcher_shared_memory.h b/content/browser/device_orientation/data_fetcher_shared_memory.h
index 8168e87134e9b119ec881f4f4da4d698320bbe2b..5461be7d66cb1458441df3f5b2a8dde78be7a0ca 100644
--- a/content/browser/device_orientation/data_fetcher_shared_memory.h
+++ b/content/browser/device_orientation/data_fetcher_shared_memory.h
@@ -16,7 +16,9 @@ namespace content {
 
 class DataFetcherSharedMemory {
  public:
-  DataFetcherSharedMemory() : device_motion_buffer_(NULL) { }
+  DataFetcherSharedMemory()
+      : device_motion_buffer_(NULL),
+        started_(false) { }
   virtual ~DataFetcherSharedMemory();
 
   // Returns true if this fetcher needs explicit calls to fetch the data.
@@ -39,6 +41,7 @@ class DataFetcherSharedMemory {
 
  private:
   DeviceMotionHardwareBuffer* device_motion_buffer_;
+  bool started_;
 
   DISALLOW_COPY_AND_ASSIGN(DataFetcherSharedMemory);
 };