Re-jigger layers

 Bug: 15185239
 Bug: 15238382

 Make DeferredLayerUpdater ref counted so that
 HardwareLayer:finalizer() works non-crashily on
 leaked layers
 Give DeferredLayerUpdater the ability to have a layer destroyer
 set so that leaked layers can still be recycled on the
 RenderThread
 Order layer updates based off of pushLayerUpdate() calls to fix
 issue with nested layers

Change-Id: I4449cee607f7e5126e02fed7464cf48038e3dfdf
diff --git a/libs/hwui/renderthread/CanvasContext.h b/libs/hwui/renderthread/CanvasContext.h
index a04269b..00c5bf0 100644
--- a/libs/hwui/renderthread/CanvasContext.h
+++ b/libs/hwui/renderthread/CanvasContext.h
@@ -55,7 +55,8 @@
     void setup(int width, int height, const Vector3& lightCenter, float lightRadius);
     void setOpaque(bool opaque);
     void makeCurrent();
-    void prepareDraw(const Vector<DeferredLayerUpdater*>* layerUpdaters, TreeInfo& info);
+    void processLayerUpdate(DeferredLayerUpdater* layerUpdater, TreeInfo& info);
+    void prepareTree(TreeInfo& info);
     void draw(Rect* dirty);
     void destroyCanvasAndSurface();
 
@@ -83,9 +84,6 @@
 private:
     friend class RegisterFrameCallbackTask;
 
-    void processLayerUpdates(const Vector<DeferredLayerUpdater*>* layerUpdaters, TreeInfo& info);
-    void prepareTree(TreeInfo& info);
-
     void setSurface(ANativeWindow* window);
     void swapBuffers();
     void requireSurface();