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

content/renderer/device_motion_event_pump.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 "device_motion_event_pump.h"
+
+#include "base/bind.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/message_loop.h"
+#include "base/shared_memory.h"
+#include "device_motion_shared_memory_reader.h"
+#include "third_party/WebKit/Source/Platform/chromium/public/WebDeviceMotionData.h"
+#include "third_party/WebKit/Source/Platform/chromium/public/WebDeviceMotionHandler.h"
+#include "third_party/WebKit/Source/Platform/chromium/public/WebDeviceMotionListener.h"
+
+namespace content {
+
+DeviceMotionEventPump::DeviceMotionEventPump()
+    : listener_(0),
+      fire_pending_(false),
+      pump_delay_(base::TimeDelta::FromMilliseconds(pump_delay_millis))
+{

[jamesr, 2013/05/16 19:53:06]

This is chromium - the { goes on the previous line here and in all other
functions

[timvolodine, 2013/05/20 18:18:48]

Done.

+}
+
+DeviceMotionEventPump::~DeviceMotionEventPump()
+{
+}
+
+void DeviceMotionEventPump::startListeningToDeviceMotion(
+    WebKit::WebDeviceMotionListener* listener)
+{
+  if (listener_)
+    return;
+
+  if (!reader_.get())
+    reader_.reset(new DeviceMotionSharedMemoryReader);
+
+  reader_->startUpdating();
+  listener_ = listener;
+
+  if (!fire_pending_) {
+    // Only post a task if the pump is not still running.
+    MessageLoop::current()->PostTask(
+        FROM_HERE,
+        base::Bind(&DeviceMotionEventPump::fire, base::Unretained(this)));

[jamesr, 2013/05/16 19:53:06]

unretained? what prevents this task from running after the pump is torn down?

I think you may want a base::RepeatingTimer here

[timvolodine, 2013/05/20 18:18:48]

switched to RepeatedTimer, looks like this is exactly what is needed.

+    fire_pending_ = true;
+  }
+}
+
+void DeviceMotionEventPump::stopListeningToDeviceMotion()
+{
+  LOG(INFO) << "stop listening\n";

[jamesr, 2013/05/16 19:53:06]

This is way too useless to spam up the INFO log.  If you want to have a way to
crank logging up for this system, consider a VLOG() or DVLOG()

[timvolodine, 2013/05/20 18:18:48]

Done.

+  reader_->stopUpdating();
+  listener_ = 0;
+}
+
+bool DeviceMotionEventPump::shouldFireEvent(WebKit::WebDeviceMotionData& data)
+{
+  // Device motion should probably be always fired,
+  // however for device orientation a threshold can be provided.
+  return true;

[jamesr, 2013/05/16 19:53:06]

why does this function take a data parameter if it doesn't use it?

[timvolodine, 2013/05/20 18:18:48]

Done.

+}
+
+void DeviceMotionEventPump::fire()
+{
+  fire_pending_ = false;
+  last_fire_event_time_ = base::TimeTicks::Now();
+
+  if (!listener_)
+    return;
+
+  WebKit::WebDeviceMotionData data;
+  if (reader_->latestDeviceMotionData(data) && shouldFireEvent(data))
+    listener_->didChangeDeviceMotion(data);
+
+  const base::TimeDelta dispatch_time =
+      base::TimeTicks::Now() - last_fire_event_time_;
+  const base::TimeDelta schedule_delay =
+      (dispatch_time < pump_delay_) ? pump_delay_ - dispatch_time
+                                    : base::TimeDelta();
+
+  MessageLoop::current()->PostDelayedTask(
+      FROM_HERE,
+      base::Bind(&DeviceMotionEventPump::fire, base::Unretained(this)),

[jamesr, 2013/05/16 19:53:06]

same thing here re the unretained

[timvolodine, 2013/05/20 18:18:48]

Done.

+      schedule_delay);
+  fire_pending_ = true;
+}
+
+
+}  // namespace content