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

content/renderer/device_orientation/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/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/message_loop.h"
+#include "base/shared_memory.h"
+#include "content/common/device_motion_messages.h"
+#include "content/public/renderer/render_thread.h"
+#include "device_motion_shared_memory_reader.h"
+#include "third_party/WebKit/public/platform/WebDeviceMotionData.h"
+#include "third_party/WebKit/public/platform/WebDeviceMotionListener.h"
+
+namespace content {
+
+const double DeviceMotionEventPump::kPumpDelayMillis = 40;
+
+DeviceMotionEventPump::DeviceMotionEventPump()
+    : listener_(0), state_(STOPPED) {
+}
+
+DeviceMotionEventPump::~DeviceMotionEventPump() {
+}
+
+bool DeviceMotionEventPump::SetListener(
+    WebKit::WebDeviceMotionListener* listener) {
+  listener_ = listener;
+  if (listener_)
+    return StartFetchingDeviceMotion();
+  return StopFetchingDeviceMotion();
+}
+
+void DeviceMotionEventPump::SetDeviceMotionReader(
+    DeviceMotionSharedMemoryReader* reader) {
+  reader_.reset(reader);

[darin (slow to review), 2013/06/17 05:27:46]

since this is a transfer of ownership, the argument type should be
scoped_ptr<DeviceMotionSharedMemoryReader>, and the callsite should use the
.Pass() method of scoped_ptr<T>.

[timvolodine, 2013/06/17 20:10:55]

Done.

+}
+
+bool DeviceMotionEventPump::StartFetchingDeviceMotion() {
+  DVLOG(2) << "start fetching device motion";
+  LOG(INFO) << "PUMP start fetching";

[darin (slow to review), 2013/06/17 05:27:46]

nit: are both of these log statements necessary?

[timvolodine, 2013/06/17 20:10:55]

sorry this was for debugging, removed all extra logging, also below.

+
+  if (state_ != STOPPED)
+    return false;
+
+  DCHECK(!timer_.IsRunning());
+
+  if (RenderThread::Get()->Send(new DeviceMotionHostMsg_StartPolling())) {
+    state_ = PENDING_START;
+    return true;
+  }
+  return false;
+}
+
+bool DeviceMotionEventPump::StopFetchingDeviceMotion() {
+  DVLOG(2) << "stop fetching device motion";
+  LOG(INFO) << "PUMP stop fetching";

[darin (slow to review), 2013/06/17 05:27:46]

ditto: can you do with only one log statement?  do you need these log statements
compiled into release builds?

[timvolodine, 2013/06/17 20:10:55]

Done.

+
+  if (state_ == STOPPED)
+    return true;
+
+  DCHECK((state_ == PENDING_START && !timer_.IsRunning())

[darin (slow to review), 2013/06/17 05:27:46]

nit: chromium style is to put the "||" operator at the end of the previous line

[timvolodine, 2013/06/17 20:10:55]

Done.

+      || (state_ == RUNNING && timer_.IsRunning()));
+
+  if (timer_.IsRunning());
+    timer_.Stop();
+  RenderThread::Get()->Send(new DeviceMotionHostMsg_StopPolling());
+  state_ = STOPPED;
+  return true;
+}
+
+void DeviceMotionEventPump::FireEvent() {
+  DCHECK(listener_);
+  LOG(INFO) << "PUMP fire";

[darin (slow to review), 2013/06/17 05:27:46]

nit: it seems like there could be a lot of these log statements in the log file.
 is this really necessary in release builds?

[timvolodine, 2013/06/17 20:10:55]

Done.

+  WebKit::WebDeviceMotionData data;
+  if (reader_->GetLatestDeviceMotionData(data))
+    listener_->didChangeDeviceMotion(data);
+}
+
+void DeviceMotionEventPump::Attach(RenderThread* thread) {
+  if (!thread)
+    return;
+  thread->AddObserver(this);
+}
+
+void DeviceMotionEventPump::OnDidStartDeviceMotion(
+     base::SharedMemoryHandle renderer_handle) {
+  DVLOG(2) << "did start fetching device motion";
+  LOG(INFO) << "PUMP did start fetching";
+
+  if (state_ != PENDING_START)
+    return;
+
+  DCHECK(!timer_.IsRunning());
+  if (!reader_)
+    SetDeviceMotionReader(new DeviceMotionSharedMemoryReader);

[darin (slow to review), 2013/06/17 05:27:46]

nit: the code might be clearer if you just directly call reader_.reset(new
DeviceMotionSharedMemoryReader) here.  since you are null testing reader_ here,
you might as well also assign to it directly.

[timvolodine, 2013/06/17 20:10:55]

Done.

+
+  if (reader_->Initialize(renderer_handle)) {
+    timer_.Start(FROM_HERE, base::TimeDelta::FromMilliseconds(kPumpDelayMillis),
+                 this, &DeviceMotionEventPump::FireEvent);
+    state_ = RUNNING;
+  }
+}
+
+bool DeviceMotionEventPump::OnControlMessageReceived(
+    const IPC::Message& message) {
+  bool handled = true;
+  IPC_BEGIN_MESSAGE_MAP(DeviceMotionEventPump, message)
+    IPC_MESSAGE_HANDLER(DeviceMotionMsg_DidStartPolling,
+        OnDidStartDeviceMotion)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+  return handled;
+}
+
+}  // namespace content