Implement Android shared memory data fetcher for Device Motion.

content/browser/device_orientation/data_fetcher_platform.cc

+// 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.
+
+#include "base/logging.h"
+#include "data_fetcher_platform.h"
+
+namespace content {
+
+SharedMemoryPlatformDataFetcherEmpty::SharedMemoryPlatformDataFetcherEmpty()
+    : device_motion_buffer_(0) {

[bulach, 2013/07/04 08:23:36]

nit: NULL

[timvolodine, 2013/07/04 12:02:52]

Done.

+}
+
+SharedMemoryPlatformDataFetcherEmpty*
+SharedMemoryPlatformDataFetcherEmpty::instance() {
+  CR_DEFINE_STATIC_LOCAL(SharedMemoryPlatformDataFetcherEmpty,
+      s_data_fetcher, ());
+  return &s_data_fetcher;
+}
+
+bool SharedMemoryPlatformDataFetcherEmpty::NeedsPolling() {
+  return false;
+}
+
+bool SharedMemoryPlatformDataFetcherEmpty::FetchDeviceMotionDataIntoBuffer() {
+  DCHECK(NeedsPolling());
+  return false;
+}
+
+bool SharedMemoryPlatformDataFetcherEmpty::StartFetchingDeviceMotionData(
+    DeviceMotionHardwareBuffer* buffer) {
+  DCHECK(buffer);
+  device_motion_buffer_->seqlock.WriteBegin();
+  device_motion_buffer_->data.allAvailableSensorsAreActive = true;
+  device_motion_buffer_->seqlock.WriteEnd();
+  return true;
+}
+
+void SharedMemoryPlatformDataFetcherEmpty::StopFetchingDeviceMotionData() {
+  device_motion_buffer_->seqlock.WriteBegin();
+  device_motion_buffer_->data.allAvailableSensorsAreActive = false;
+  device_motion_buffer_->seqlock.WriteEnd();
+}
+
+}  // namespace content