Implement the content/renderer and content/browser part of the Device Motion API.

content/renderer/device_orientation/device_motion_event_pump.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_RENDERER_DEVICE_MOTION_EVENT_PUMP_H_
+#define CONTENT_RENDERER_DEVICE_MOTION_EVENT_PUMP_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "base/shared_memory.h"
+#include "base/timer/timer.h"
+#include "content/public/renderer/render_process_observer.h"
+#include "content/renderer/shared_memory_seqlock_reader.h"
+#include "third_party/WebKit/public/platform/WebDeviceMotionData.h"
+
+namespace WebKit {
+class WebDeviceMotionListener;
+}
+
+namespace content {
+class RenderThread;
+
+typedef SharedMemorySeqLockReader<WebKit::WebDeviceMotionData>
+    DeviceMotionSharedMemoryReader;
+
+class CONTENT_EXPORT DeviceMotionEventPump : public RenderProcessObserver {
+ public:
+  DeviceMotionEventPump();
+  virtual ~DeviceMotionEventPump();
+
+  static double GetDelayMillis();
+
+  // Sets the listener to receive updates for device motion data at
+  // regular intervals.
+  // Returns true if the registration was successful.
+  bool SetListener(WebKit::WebDeviceMotionListener*);
+
+  void SetDeviceMotionReader(scoped_ptr<DeviceMotionSharedMemoryReader>);
+
+  void Attach(RenderThread* thread);
+
+  // RenderProcessObserver implementation.
+  virtual bool OnControlMessageReceived(const IPC::Message& message) OVERRIDE;
+
+ protected:
+  // Delay between subsequent firing of events.
+  static const double kPumpDelayMillis;
+
+  // The pump is a tri-state automaton with allowed transitions as follows:
+  // STOPPED -> PENDING_START
+  // PENDING_START -> RUNNING
+  // PENDING_START -> STOPPED
+  // RUNNING -> STOPPED
+  enum PumpState {
+      STOPPED,
+      RUNNING,
+      PENDING_START
+  };
+
+  bool StartFetchingDeviceMotion();
+  bool StopFetchingDeviceMotion();
+  void OnDidStartDeviceMotion(base::SharedMemoryHandle renderer_handle);
+  void FireEvent();
+
+  WebKit::WebDeviceMotionListener* listener_;
+  scoped_ptr<DeviceMotionSharedMemoryReader> reader_;
+  base::RepeatingTimer<DeviceMotionEventPump> timer_;
+  PumpState state_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_DEVICE_MOTION_EVENT_PUMP_H_