Move OpenGL specific details behind renderPipeline interface.

Test: new and existing unit tests still pass.
Change-Id: I6164f30f45ebe450788ed8d949eca5af9a44e585
diff --git a/libs/hwui/renderthread/CanvasContext.h b/libs/hwui/renderthread/CanvasContext.h
index 125f109..b61eef2 100644
--- a/libs/hwui/renderthread/CanvasContext.h
+++ b/libs/hwui/renderthread/CanvasContext.h
@@ -85,6 +85,10 @@
      */
     static void destroyLayer(RenderNode* node);
 
+    static void invokeFunctor(const RenderThread& thread, Functor* functor);
+
+    static void prepareToDraw(const RenderThread& thread, Bitmap* bitmap);
+
     /*
      * If Properties::isSkiaEnabled() is true then this will return the Skia
      * grContext associated with the current RenderPipeline.
@@ -121,8 +125,6 @@
     void destroyHardwareResources(TreeObserver* observer);
     static void trimMemory(RenderThread& thread, int level);
 
-    static void invokeFunctor(RenderThread& thread, Functor* functor);
-
     DeferredLayerUpdater* createTextureLayer();
 
     void stopDrawing();