Aura: Resize locks with --ui-enable-threaded-compositing

cc/proxy.h

Index: cc/proxy.h
diff --git a/cc/proxy.h b/cc/proxy.h
index daddadeeb10ed45e697faa59f50b8cc283dccd5d..0f8dca1650ebb7c591f343a1eff3e89cb1132e61 100644
--- a/cc/proxy.h
+++ b/cc/proxy.h
@@ -65,6 +65,11 @@ public:
     virtual void setNeedsCommit() = 0;
     virtual void setNeedsRedraw() = 0;
 
+    // Defers commits until it is reset. Certain actions may forcibly allow commits to go through (we post
+    // a task with a reset in the common case). So it is important that we always be in a comittable state.

[jamesr, 2012/10/23 21:24:34]

not sure what exactly this comment is referring to - are you trying to say that
we might commit even if deferCommits is set, so the LayerTreeHost has to be
committable?  Such a comment would better fit on LayerTreeHost

I think it's really important to think about what this API means in terms of
interactions between the embedder and cc.  This call is a way for the embedder
to communicate to cc that it doesn't want cc to commit of its own volition, but
if the embedder makes a sync call that requires a commit (like
compositeAndReadback) it will still happen.

[jonathan.backer, 2012/10/24 16:42:14]

Based on some of your earlier comments, it is an error to make a sync call if it
is deferred. We'll let aura do what it wants. But there is no requirement that
we be in a commitable state at the cc level.

As this is a thread only feature, I feel like the comment belongs here. But I am
more than happy to move it.

+    virtual void setDeferCommits(bool) = 0;
+    virtual bool deferCommits() const = 0;
+
     virtual void didAddAnimation() = 0;
 
     virtual bool commitRequested() const = 0;