Battery Status API: blink promise implementation and layout tests.

Source/modules/battery/BatteryManager.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/BatteryManager.h"
 
 #include "RuntimeEnabledFeatures.h"
 #include "modules/battery/BatteryDispatcher.h"
 #include "modules/battery/BatteryStatus.h"
 
 namespace WebCore {
 
 PassRefPtrWillBeRawPtr<BatteryManager> BatteryManager::create(ExecutionContext* context)
 {
     RefPtrWillBeRawPtr<BatteryManager> batteryManager(adoptRefWillBeRefCountedGarbageCollected(new BatteryManager(context)));
     batteryManager->suspendIfNeeded();
     return batteryManager.release();
 }
 
+class BatteryManager::ThenFunction FINAL : public ScriptFunction {
+public:
+    static PassOwnPtr<ScriptFunction> create(PassRefPtr<BatteryManager> observer)
+    {
+        ExecutionContext* executionContext = observer->executionContext();
+        return adoptPtr(new ThenFunction(toIsolate(executionContext), observer));
+    }
+private:
+    ThenFunction(v8::Isolate* isolate, PassRefPtr<BatteryManager> observer)
+        : ScriptFunction(isolate)
+        , m_observer(observer)
+    {
+    }
+
+    virtual ScriptValue call(ScriptValue value) OVERRIDE
+    {
+        m_observer->onPromiseResolved();
+        return value;
+    }
+
+    RefPtr<BatteryManager> m_observer;
+};
+
 BatteryManager::~BatteryManager()
 {
     stopUpdating();
 }
 
 BatteryManager::BatteryManager(ExecutionContext* context)
     : ActiveDOMObject(context)
     , DeviceEventControllerBase(toDocument(context)->page())
     , m_batteryStatus(BatteryStatus::create())
+    , m_state(NotStarted)
 {
+}
+
+ScriptPromise BatteryManager::startRequest(ScriptState* scriptState)
+{
+    if (m_state == Pending)
+        return m_resolver->promise();
+
+    m_resolver = ScriptPromiseResolverWithContext::create(scriptState);
+    ScriptPromise promise = m_resolver->promise();
+
+    if (m_state == Resolved) {
+        m_resolver->resolve(this);
+        return promise;
+    }

[abarth-chromium, 2014/06/11 19:44:34]

Why not just return m_resolver->promise(); at this point?

[timvolodine, 2014/06/12 16:38:45]

slightly refactored this code. Done.

+
+    m_state = Pending;
     m_hasEventListener = true;
+    promise.then(ThenFunction::create(this));

[abarth-chromium, 2014/06/11 19:44:34]

Why do we need to create a ThenFunction instead of just setting m_state =
Resolved near line 116?

[timvolodine, 2014/06/12 16:38:45]

yeah on second thought the "ThenFunction" seems like overkill. Done.

     startUpdating();
+    return promise;
+}
+
+void BatteryManager::onPromiseResolved()
+{
+    ASSERT(m_state == Pending);
+    m_state = Resolved;
 }
 
 bool BatteryManager::charging()
 {
     return m_batteryStatus->charging();
 }
 
 double BatteryManager::chargingTime()
 {
     return m_batteryStatus->chargingTime();
 }
 
 double BatteryManager::dischargingTime()
 {
     return m_batteryStatus->dischargingTime();
 }
 
 double BatteryManager::level()
 {
     return m_batteryStatus->level();
 }
 
 void BatteryManager::didUpdateData()
 {
     ASSERT(RuntimeEnabledFeatures::batteryStatusEnabled());
+    ASSERT(m_state != NotStarted);
 
     RefPtr<BatteryStatus> oldStatus = m_batteryStatus;
     m_batteryStatus = BatteryDispatcher::instance().latestData();
 
     // BatteryDispatcher also holds a reference to m_batteryStatus.
     ASSERT(m_batteryStatus->refCount() > 1);
 
+    if (m_state == Pending && m_resolver) {
+        ASSERT(m_resolver);
+        m_resolver->resolve(this);
+        return;
+    }
+
     Document* document = toDocument(executionContext());
     if (document->activeDOMObjectsAreSuspended() || document->activeDOMObjectsAreStopped())
         return;
 
     ASSERT(oldStatus);
 
     if (m_batteryStatus->charging() != oldStatus->charging())
         dispatchEvent(Event::create(EventTypeNames::chargingchange));
     if (m_batteryStatus->chargingTime() != oldStatus->chargingTime())
         dispatchEvent(Event::create(EventTypeNames::chargingtimechange));
@@ skipping 30 matching lines @@
     startUpdating();
 }
 
 void BatteryManager::stop()
 {
     m_hasEventListener = false;
     stopUpdating();
 }
 
 } // namespace WebCore