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 c2605c157caa2787a5da09895322d8aa52a7ff66..7b635016c2b10687d0001547dd8a9bc2428aaf6b 100644
--- a/Source/modules/webaudio/DeferredTaskHandler.cpp
+++ b/Source/modules/webaudio/DeferredTaskHandler.cpp
@@ -42,6 +42,19 @@ void DeferredTaskHandler::lock()
     m_contextGraphMutex.lock();
 }
 
+void DeferredTaskHandler::forceLock()
+{
+    // This allows the regular lock in non-real-time audio thread.
+    ASSERT(!isMainThread());
+    if (isMainThread()) {
+        // If this gets called in the main thread, do tryLock() instead.
+        m_contextGraphMutex.tryLock();

[haraken, 2015/06/17 06:46:08]

Two questions:

- This can fail. Is it OK?
- Why does the main thread need to use tryLock()? The main thread is not a
realtime thread.

[hongchan, 2015/06/17 20:10:39]

For this pattern, I would like to ask your opinion. I just want to be able to
lock the graph in the offline audio rendering. What would be the most
simple/elegant? Just lock() it?

+        return;
+    }
+
+    m_contextGraphMutex.lock();
+}
+
 bool DeferredTaskHandler::tryLock()
 {
     // Try to catch cases of using try lock on main thread