Generalize and refactor DeviceSensorEvent* architecture to support multi-event type targets.

Source/modules/battery/BatteryDispatcher.cpp

Index: Source/modules/battery/BatteryDispatcher.cpp
diff --git a/Source/modules/battery/BatteryDispatcher.cpp b/Source/modules/battery/BatteryDispatcher.cpp
index 515c49a7c6149a9c6c11f772f60d55bf1bede3f4..6b49a6c523051c8a4f8774c0aed96bde6c4f4ec4 100644
--- a/Source/modules/battery/BatteryDispatcher.cpp
+++ b/Source/modules/battery/BatteryDispatcher.cpp
@@ -25,61 +25,15 @@ 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> oldStatus = m_batteryStatus;
     m_batteryStatus = BatteryStatus::create(batteryStatus.charging, batteryStatus.chargingTime, batteryStatus.dischargingTime, batteryStatus.level);
-
-    if (oldStatus) {
-        if (m_batteryStatus->charging() != oldStatus->charging())
-            didChangeBatteryStatus(EventTypeNames::chargingchange);
-        if (m_batteryStatus->charging() && m_batteryStatus->chargingTime() != oldStatus->chargingTime())
-            didChangeBatteryStatus(EventTypeNames::chargingtimechange);
-        if (!m_batteryStatus->charging() && m_batteryStatus->dischargingTime() != oldStatus->dischargingTime())
-            didChangeBatteryStatus(EventTypeNames::dischargingtimechange);
-        if (m_batteryStatus->level() != oldStatus->level())
-            didChangeBatteryStatus(EventTypeNames::levelchange);
-    } else {
-        // There was no previous state.
-        didChangeBatteryStatus(EventTypeNames::chargingchange);
-        didChangeBatteryStatus(EventTypeNames::chargingtimechange);
-        didChangeBatteryStatus(EventTypeNames::dischargingtimechange);
-        didChangeBatteryStatus(EventTypeNames::levelchange);
-    }
-
-}
-
-const BatteryStatus* BatteryDispatcher::getLatestData()
-{
-    return m_batteryStatus.get();
+    notifyControllers();
 }
 
-void BatteryDispatcher::didChangeBatteryStatus(const AtomicString& eventType)
+PassRefPtr<BatteryStatus> BatteryDispatcher::getLatestData()

[Inactive, 2014/06/03 13:49:33]

It seems weird to return a PassRefPtr here since we are not transferring
ownership to the caller. In such cases, the convention in Blink is to return a
raw pointer.

[timvolodine, 2014/06/03 18:45:54]

The idea is to share the RefPtr with the BatteryManager class, i.e.
BatteryManager can keep a reference to this same data. That way no copying is
necessary and the actual refptr would be deleted only if both BatteryManager and
Dispatcher abandon it. For example SVGPathSegList::getItem() seems to perform a
similar approach.

[Inactive, 2014/06/03 19:04:23]

The fact that you are returning a raw pointer here does not prevent
BatteryManager from storing the return value in a RefPtr. This is a separate
issue. Our convention, as far as I know (I have been corrected in the past on
this matter), is that we return PassRefPtr<> only if we transfer ownership to
the caller (e.g. a factory function). For other cases, we return a raw pointer.
You are going to find some counter-examples in the code base, but it does not
mean that that code is right :)

 {
-    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();
+    return m_batteryStatus;
 }
 
 void BatteryDispatcher::startListening()
@@ -90,6 +44,7 @@ void BatteryDispatcher::startListening()
 void BatteryDispatcher::stopListening()
 {
     blink::Platform::current()->setBatteryStatusListener(0);
+    m_batteryStatus.clear();
 }
 
 }