Add Dispatcher class to the Battery Status API module.

Source/modules/battery/BatteryDispatcher.cpp

+// 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 "config.h"
+#include "modules/battery/BatteryDispatcher.h"
+
+#include "core/events/Event.h"
+#include "modules/battery/BatteryStatus.h"
+#include "public/platform/Platform.h"
+
+namespace WebCore {
+
+BatteryDispatcher& BatteryDispatcher::instance()
+{
+    DEFINE_STATIC_LOCAL(BatteryDispatcher, batteryDispatcher, ());
+    return batteryDispatcher;
+}
+
+BatteryDispatcher::BatteryDispatcher()
+{
+}
+
+BatteryDispatcher::~BatteryDispatcher()
+{
+}
+
+void BatteryDispatcher::addClient(BatteryManager* batteryManager)
+{
+    addController(batteryManager);
+}
+
+void BatteryDispatcher::removeClient(BatteryManager* batteryManager)
+{
+    removeController(batteryManager);
+}
+
+void BatteryDispatcher::updateBatteryStatus(const blink::WebBatteryStatus& batteryStatus)
+{
+    RefPtr<BatteryStatus> status = BatteryStatus::create(batteryStatus.charging, batteryStatus.chargingTime, batteryStatus.dischargingTime, batteryStatus.level);

[timvolodine, 2014/04/09 15:19:18]

could you just do:
RefPtr<BatteryStatus> oldStatus = m_batteryStatus;
m_batteryStatus = BatteryStatus::create(...);

[Srini, 2014/04/09 16:09:57]

I thought of this, but then I wanted to find the case of no previous status, i.e
no m_batteryStatus and getting it fresh from the platform. May be I can find
that save in a flag before I do this. I'll fix this.

[timvolodine, 2014/04/09 18:59:02]

I am not exactly sure what you mean, can you just use if(oldStatus) to see if
there is anything previously.

+
+    if (m_batteryStatus) {
+        RefPtr<BatteryStatus> oldStatus = m_batteryStatus.release();
+        m_batteryStatus = status.release();
+
+        if (m_batteryStatus->charging() != status->charging())
+            didChangeBatteryStatus(EventTypeNames::chargingchange);
+        if (status->charging() && m_batteryStatus->chargingTime() != status->chargingTime())
+            didChangeBatteryStatus(EventTypeNames::chargingtimechange);
+        if (!status->charging() && m_batteryStatus->dischargingTime() != status->dischargingTime())
+            didChangeBatteryStatus(EventTypeNames::dischargingtimechange);
+        if (m_batteryStatus->level() != status->level())
+            didChangeBatteryStatus(EventTypeNames::levelchange);
+    } else {
+        // There was no previous state.
+        m_batteryStatus = status.release();
+        didChangeBatteryStatus(EventTypeNames::chargingchange);

[timvolodine, 2014/04/09 15:19:18]

also fire dischargingchange?

[Srini, 2014/04/09 16:09:57]

This is the first time event fire. I wasn't sure, should I emit all or just send
few. May be I should check values between default and actual and fire
accordingly?

[timvolodine, 2014/04/09 18:59:02]

I think you should fire all, if chrome cannot provide data for some reason it
can still fire with default values.

+        didChangeBatteryStatus(EventTypeNames::levelchange);
+    }
+
+}
+
+const BatteryStatus* BatteryDispatcher::getLatestData()
+{
+    if (m_batteryStatus)

[timvolodine, 2014/04/09 15:19:18]

no need for if, just return m_batteryStatus.get();

[Srini, 2014/04/09 16:09:57]

ok.

+        return m_batteryStatus.get();
+
+    return 0;
+}
+
+void BatteryDispatcher::didChangeBatteryStatus(const AtomicString& eventType)
+{
+    RefPtrWillBeRawPtr<Event> event = Event::create(eventType);
+
+    {
+        TemporaryChange<bool> changeIsDispatching(m_isDispatching, true);
+        // Don't fire listeners removed or added during event dispatch.
+        size_t size = m_controllers.size();
+        for (size_t i = 0; i < size; ++i) {
+            if (m_controllers[i])
+                static_cast<BatteryManager*>(m_controllers[i])->didChangeBatteryStatus(event);
+        }
+    }
+
+    if (m_needsPurge)
+        purgeControllers();
+}
+
+void BatteryDispatcher::startListening()
+{
+    // blink::Platform::current()->setBatteryListener(this);
+}
+
+void BatteryDispatcher::stopListening()
+{
+    // blink::Platform::current()->setBatteryListener(0);
+}
+
+}