Implement suspend() and resume() for OfflineAudioContext

Source/modules/webaudio/DeferredTaskHandler.cpp

Index: Source/modules/webaudio/DeferredTaskHandler.cpp
diff --git a/Source/modules/webaudio/DeferredTaskHandler.cpp b/Source/modules/webaudio/DeferredTaskHandler.cpp
index e5ded30448748d06e92bb85998c3243ef5dc2d82..339e3fd9b32f5cfdaa28c5529ac7bb2733935b78 100644
--- a/Source/modules/webaudio/DeferredTaskHandler.cpp
+++ b/Source/modules/webaudio/DeferredTaskHandler.cpp
@@ -41,6 +41,14 @@ void DeferredTaskHandler::lock()
     m_contextGraphMutex.lock();
 }
 
+void DeferredTaskHandler::forceLock()
+{
+    // This allows the regular lock in offline audio rendering. It is okay to

[tkent, 2015/07/16 00:33:43]

Such comment should be in the header.

[hongchan, 2015/07/16 16:22:18]

Done.

+    // lock the offline audio render thread because it is not real-time thread.
+    ASSERT(!isMainThread());
+    m_contextGraphMutex.lock();
+}
+
 bool DeferredTaskHandler::tryLock()
 {
     // Try to catch cases of using try lock on main thread