Implement Device Orientation using shared memory in content/renderer.

content/renderer/device_orientation/device_orientation_event_pump.h

+// Copyright 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_RENDERER_DEVICE_ORIENTATION_EVENT_PUMP_H_
+#define CONTENT_RENDERER_DEVICE_ORIENTATION_EVENT_PUMP_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "content/renderer/device_orientation/device_sensor_event_pump.h"
+#include "content/renderer/shared_memory_seqlock_reader.h"
+#include "third_party/WebKit/public/platform/WebDeviceOrientationData.h"
+
+namespace WebKit {
+class WebDeviceOrientationListener;
+}
+
+namespace content {
+
+typedef SharedMemorySeqLockReader<WebKit::WebDeviceOrientationData>
+    DeviceOrientationSharedMemoryReader;
+
+class CONTENT_EXPORT DeviceOrientationEventPump : public DeviceSensorEventPump {
+ public:
+  // Angle threshold beyond which two orientation events are considered
+  // sufficiently different.
+  static const double kOrientationThreshold;
+
+  DeviceOrientationEventPump();
+  explicit DeviceOrientationEventPump(int pump_delay_millis);
+  virtual ~DeviceOrientationEventPump();
+
+  // Sets the listener to receive updates for device orientation data at
+  // regular intervals. Returns true if the registration was successful.
+  bool SetListener(WebKit::WebDeviceOrientationListener* listener);
+
+  // RenderProcessObserver implementation.
+  virtual bool OnControlMessageReceived(const IPC::Message& message) OVERRIDE;
+
+ protected:
+  virtual void FireEvent() OVERRIDE;
+  virtual bool InitializeReader(base::SharedMemoryHandle handle) OVERRIDE;
+  virtual bool SendStartMessage() OVERRIDE;
+  virtual bool SendStopMessage() OVERRIDE;
+
+  bool ShouldFireEvent(const WebKit::WebDeviceOrientationData& data) const;
+
+  WebKit::WebDeviceOrientationListener* listener_;
+  WebKit::WebDeviceOrientationData data_;
+  scoped_ptr<DeviceOrientationSharedMemoryReader> reader_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_DEVICE_ORIENTATION_EVENT_PUMP_H_