Implement Android shared memory data fetcher for Device Motion.

content/browser/device_orientation/data_fetcher_shared_memory.h

+// Copyright (c) 2013 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 CONTENT_BROWSER_DEVICE_ORIENTATION_DATA_FETCHER_SHARED_MEMORY_H_
+#define CONTENT_BROWSER_DEVICE_ORIENTATION_DATA_FETCHER_SHARED_MEMORY_H_
+
+#include "content/browser/device_orientation/device_data.h"
+#include "content/common/device_motion_hardware_buffer.h"
+
+namespace WebKit {
+class WebDeviceMotionData;
+}
+
+namespace content {
+
+class DataFetcherSharedMemory {
+ public:
+  DataFetcherSharedMemory() : device_motion_buffer_(NULL) { }
+  virtual ~DataFetcherSharedMemory();
+
+  // Returns true if this fetcher needs explicit calls to fetch the data.
+  virtual bool NeedsPolling();
+
+  // If this fetcher NeedsPolling() is true, this method will update the
+  // buffer with the latest device motion data.
+  // This method will do nothing if NeedsPolling() is false.
+  // Returns true if there was any motion data to update the buffer with.
+  virtual bool FetchDeviceMotionDataIntoBuffer();
+
+  // Returns true if the relevant sensors could be successfully activated.
+  // This method should be called before any calls to
+  // FetchDeviceMotionDataIntoBuffer().
+  virtual bool StartFetchingDeviceMotionData(
+      DeviceMotionHardwareBuffer* buffer);
+
+  // Indicates to the fetcher to stop fetching device data.
+  virtual void StopFetchingDeviceMotionData();
+
+ private:
+  DeviceMotionHardwareBuffer* device_motion_buffer_;
+
+  DISALLOW_COPY_AND_ASSIGN(DataFetcherSharedMemory);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_DEVICE_ORIENTATION_DATA_FETCHER_SHARED_MEMORY_H_