cc: Block commit on activate by setting a flag on LayerTreeHost.

cc/trees/layer_tree_host.h

Index: cc/trees/layer_tree_host.h
diff --git a/cc/trees/layer_tree_host.h b/cc/trees/layer_tree_host.h
index 619c18e6574fe057bb1356a87ff754d68c3196b5..b4d6e7975330b335970bc5875a6c27b754373a6b 100644
--- a/cc/trees/layer_tree_host.h
+++ b/cc/trees/layer_tree_host.h
@@ -266,7 +266,12 @@ class CC_EXPORT LayerTreeHost : NON_EXPORTED_BASE(public RateLimiterClient) {
     return animation_registrar_.get();
   }
 
-  bool BlocksPendingCommit() const;
+  void SetNextCommitWaitsForActivation() {
+    commit_waits_for_activation_ = true;

[danakj, 2013/08/29 01:58:18]

It occured to me, maybe this should just set a bit on the proxy, so the proxy
doesn't have to read it off the LTH later, and it can reset it once it's done
with it. Less magical maybe?

I'll do it this way tomorrow if no one cries foul.

+  }
+  bool CommitWaitsForActivation() const {
+    return commit_waits_for_activation_;
+  }
 
   // Obtains a thorough dump of the LayerTreeHost as a value.
   scoped_ptr<base::Value> AsValue() const;
@@ -335,6 +340,7 @@ class CC_EXPORT LayerTreeHost : NON_EXPORTED_BASE(public RateLimiterClient) {
   bool animating_;
   bool needs_full_tree_sync_;
   bool needs_filter_context_;
+  bool commit_waits_for_activation_;
 
   base::CancelableClosure prepaint_callback_;