Implement suspend() and resume() for OfflineAudioContext

third_party/WebKit/Source/modules/webaudio/AudioNode.h

Index: third_party/WebKit/Source/modules/webaudio/AudioNode.h
diff --git a/third_party/WebKit/Source/modules/webaudio/AudioNode.h b/third_party/WebKit/Source/modules/webaudio/AudioNode.h
index 1a7d57a70d0d0b146566622e74a0178a67bde359..c055ba833158ccb6c3d0eedd0cfbb0e614191928 100644
--- a/third_party/WebKit/Source/modules/webaudio/AudioNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/AudioNode.h
@@ -107,7 +107,7 @@ public:
     // nullptr otherwise.  This always returns a valid object in an audio
     // rendering thread, and inside dispose().  We must not call context() in
     // the destructor.
-    AbstractAudioContext* context() const;
+    virtual AbstractAudioContext* context() const;
     void clearContext() { m_context = nullptr; }
 
     enum ChannelCountMode {
@@ -229,6 +229,12 @@ protected:
     // Force all inputs to take any channel interpretation changes into account.
     void updateChannelsForInputs();
 
+    // This raw pointer is safe because this is cleared for all of live
+    // AudioHandlers when the AbstractAudioContext dies.  Do not access m_context
+    // directly, use context() instead.
+    GC_PLUGIN_IGNORE("http://crbug.com/404527")
+    AbstractAudioContext* m_context;

[haraken, 2015/11/17 08:28:10]

Why do we need to move m_context to a protected member? As mentioned in the
comment, m_context must be accessed via context().

[hongchan, 2015/11/17 18:11:44]

1. OfflineAudioDestinationNode (inherited from AudioNode) needs to access
m_context,
2. Because its override method context() returns OfflineAudioContext* instead of
AbstractAudioContext*. (See line 110)

If you have a better way to structure this, I can certainly change this.

[haraken, 2015/11/18 00:20:26]

- Rename OfflineAudioDestinationNode::context() to
OfflineAudioDestinationNode::offlineAudioContext().

- Keep AudioNode::context() non-virtual.

- OfflineAudioDestinationNode::offlineAudioContext() calls
static_cast<OfflineAudioContext*>(context()).

?

[hongchan, 2015/11/18 17:23:48]

Yes, it is obvious thing to do - but 'context()' is used at so many places in
OfflineAudioDestinationNode. So I did not want to replace all the instances of
'context()' with something new, mainly to keep the render process same.

I do not have a strong opinion on this, so I can fix it if you prefer to have
this change.

+
 private:
     void setNodeType(NodeType);
 
@@ -241,12 +247,6 @@ private:
     GC_PLUGIN_IGNORE("http://crbug.com/404527")
     AudioNode* m_node;
 
-    // This raw pointer is safe because this is cleared for all of live
-    // AudioHandlers when the AbstractAudioContext dies.  Do not access m_context
-    // directly, use context() instead.
-    GC_PLUGIN_IGNORE("http://crbug.com/404527")
-    AbstractAudioContext* m_context;
-
     float m_sampleRate;
     Vector<OwnPtr<AudioNodeInput>> m_inputs;
     Vector<OwnPtr<AudioNodeOutput>> m_outputs;