WebKit & WebCore part of the device motion implementation using the platform layer.

Source/WebCore/platform/chromium/support/WebDeviceMotionEventPump.h

+/*
+ * Copyright (C) 2013 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef WebDeviceMotionEventPump_h
+#define WebDeviceMotionEventPump_h
+
+#include "Timer.h"
+#include <DeviceMotionController.h>
+#include <DeviceMotionData.h>
+#include <wtf/HashCountedSet.h>
+#include <wtf/RefCounted.h>
+
+using WebCore::DeviceMotionController;
+using WebCore::DeviceMotionData;
+using WebCore::Timer;
+
+namespace WebKit {
+
+// FIXME: implement a superclass for this, because we will also use
+// a pump for the device orientation events.
+class WebDeviceMotionEventPump {
+public:
+    static const double kPumpDelayMilliseconds = 100;

[eseidel, 2013/04/23 15:21:24]

Is this the delay between events?  This appears to be just a default which
create() uses?

[timvolodine, 2013/04/23 18:10:40]

yes. It is also used by WebDeviceMotionData to set the interval field in
DeviceMotionData.

+
+    static WebDeviceMotionEventPump& shared();
+
+    void addListener(DeviceMotionController*);
+    void removeListener(DeviceMotionController*);
+
+    // The returned pointer is owned by this class.
+    // FIXME: make the return value const, see crbug/233174.

[eseidel, 2013/04/23 15:21:24]

Nit: Comments should start with a capital, end with a period.

[timvolodine, 2013/04/23 18:10:40]

Done.

+    DeviceMotionData* latestDeviceMotionData();
+
+private:
+    WebDeviceMotionEventPump(double delaySeconds);
+    ~WebDeviceMotionEventPump() { }

[eseidel, 2013/04/23 15:21:24]

Are you sure you want this inline (and thus declared in every compilation unit
which uses it?)

[timvolodine, 2013/04/23 18:10:40]

Done.

+
+    void start();
+    void stop();
+    void scheduleFireEvent();
+    void fireEvent(Timer<WebDeviceMotionEventPump>*);
+    bool shouldFireEvent();
+
+    double m_delaySeconds;
+    double m_lastFireEventTimeMonotonic;
+    bool m_stopped;
+    RefPtr<DeviceMotionData> m_lastDeviceMotionData;
+    Timer<WebDeviceMotionEventPump> m_pumpTimer;
+    HashCountedSet<RefPtr<DeviceMotionController> > m_listeners;
+};
+
+} // namespace WebKit
+
+#endif