cc: Allow the main thread to cancel commits

cc/test/fake_content_layer.h

Index: cc/test/fake_content_layer.h
diff --git a/cc/test/fake_content_layer.h b/cc/test/fake_content_layer.h
index 6b7a37d4c83bbace6191493781330d5b84c4ca70..191a634efd07e2eeb3e1fa782527ab7f28d85330 100644
--- a/cc/test/fake_content_layer.h
+++ b/cc/test/fake_content_layer.h
@@ -29,6 +29,10 @@ class FakeContentLayer : public ContentLayer {
       ResourceUpdateQueue* queue,
       const OcclusionTracker* occlusion) OVERRIDE;
 
+  void set_always_update_resources(bool always_update_resources) {
+    always_update_resources_ = always_update_resources;
+  }
+
   virtual void PushPropertiesTo(LayerImpl* layer) OVERRIDE;
 
   bool HaveBackingAt(int i, int j);
@@ -39,6 +43,7 @@ class FakeContentLayer : public ContentLayer {
 
   size_t update_count_;
   size_t push_properties_count_;
+  bool always_update_resources_;
 };
 
 }  // namespace cc