Implement suspend() and resume() for OfflineAudioContext

Source/modules/webaudio/OfflineAudioContext.h

Index: Source/modules/webaudio/OfflineAudioContext.h
diff --git a/Source/modules/webaudio/OfflineAudioContext.h b/Source/modules/webaudio/OfflineAudioContext.h
index 99276e7cbb5e19dc7edf2934b67a726f2eed8d2a..2b613f83e1b7c17ddee61e019cb920a6c6000f30 100644
--- a/Source/modules/webaudio/OfflineAudioContext.h
+++ b/Source/modules/webaudio/OfflineAudioContext.h
@@ -36,12 +36,23 @@ class MODULES_EXPORT OfflineAudioContext final : public AudioContext {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static OfflineAudioContext* create(ExecutionContext*, unsigned numberOfChannels, size_t numberOfFrames, float sampleRate, ExceptionState&);
-
     virtual ~OfflineAudioContext();
 
+    virtual bool suspendIfNecessary();
+
+    // IDL implementations.
     ScriptPromise startOfflineRendering(ScriptState*);
+    ScriptPromise suspendOfflineRendering(ScriptState*, double suspendTime);
+    ScriptPromise resumeOfflineRendering(ScriptState*);
+
 private:
     OfflineAudioContext(Document*, unsigned numberOfChannels, size_t numberOfFrames, float sampleRate);
+
+    WillBeHeapVector<RefPtrWillBeMember<ScriptPromiseResolver>> m_offlineSuspendResolvers;
+    WillBeHeapVector<RefPtrWillBeMember<ScriptPromiseResolver>> m_offlineResumeResolvers;

[Raymond Toy, 2015/05/13 17:16:08]

As discussed earlier, the online context is going to merge the suspend resume
resolvers onto one list/vector so that they happen in order.  Does that matter
here?

[hongchan, 2015/05/13 17:30:53]

Yes. That makes sense. These are actually not used in this patch at all - they
are just placeholders.

+
+    bool m_isSuspendScheduled;
+    double m_suspendTime;
 };
 
 } // namespace blink