Add Battery Status API support in content/renderer and IPC messages.

content/renderer/battery_status/battery_status_dispatcher.cc

+// Copyright 2014 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 "battery_status_dispatcher.h"
+
+#include "base/logging.h"
+#include "content/common/battery_status_messages.h"
+#include "content/renderer/render_thread_impl.h"
+#include "third_party/WebKit/public/platform/WebBatteryStatusListener.h"
+
+namespace content {
+
+BatteryStatusDispatcher::BatteryStatusDispatcher(RenderThread* thread)
+    : listener_(0) {
+  if (thread)
+    thread->AddObserver(this);
+}
+
+BatteryStatusDispatcher::~BatteryStatusDispatcher() { }

[jochen (gone - plz use gerrit), 2014/05/02 14:08:53]

should this invoke Stop() if listener_ is non-NULL?

[timvolodine, 2014/05/02 15:03:55]

Done.

+
+bool BatteryStatusDispatcher::SetListener(
+    blink::WebBatteryStatusListener* listener) {
+  listener_ = listener;
+  return listener ? Start() : Stop();
+}
+
+bool BatteryStatusDispatcher::OnControlMessageReceived(
+    const IPC::Message& message) {
+  bool handled = true;
+  IPC_BEGIN_MESSAGE_MAP(BatteryStatusDispatcher, message)
+    IPC_MESSAGE_HANDLER(BatteryStatusMsg_DidChange, OnDidChange)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+  return handled;
+}
+
+bool BatteryStatusDispatcher::Start() {
+  return RenderThread::Get()->Send(new BatteryStatusHostMsg_Start());
+}
+
+bool BatteryStatusDispatcher::Stop() {
+  return RenderThread::Get()->Send(new BatteryStatusHostMsg_Stop());
+}
+
+void BatteryStatusDispatcher::OnDidChange(
+    const blink::WebBatteryStatus& status) {
+  if (listener_)
+    listener_->updateBatteryStatus(status);
+}
+
+}  // namespace content