add ability to get FBO ID to Surface

include/core/SkSurface.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkSurface_DEFINED
 #define SkSurface_DEFINED
 
@@ skipping 125 matching lines @@
     };
 
     /**
      *  Call this if the contents are about to change. This will (lazily) force a new
      *  value to be returned from generationID() when it is called next.
      *
      *  CAN WE DEPRECATE THIS?
      */
     void notifyContentWillChange(ContentChangeMode mode);
 
-    enum TextureHandleAccess {
-        kFlushRead_TextureHandleAccess,     //!< caller may read from the texture
-        kFlushWrite_TextureHandleAccess,    //!< caller may write to the texture
-        kDiscardWrite_TextureHandleAccess,  //!< caller must over-write the entire texture
+    enum BackendHandleAccess {
+        kFlushRead_BackendHandleAccess,     //!< caller may read from the backend object
+        kFlushWrite_BackendHandleAccess,    //!< caller may write to the backend object
+        kDiscardWrite_BackendHandleAccess,  //!< caller must over-write the entire backend object
     };
     /**
      *  Retrieves the backend API handle of the texture used by this surface, or 0 if the surface
      *  is not backed by a GPU texture.
      *
      *  The returned texture-handle is only valid until the next draw-call into the surface,
      *  or the surface is deleted.
      */
-    GrBackendObject getTextureHandle(TextureHandleAccess);
+    GrBackendObject getTextureHandle(BackendHandleAccess);
+
+    /**
+     *  Retrieves the backend API handle of the RenderTarget backing this surface.  Callers must

[robertphillips, 2015/07/06 15:29:02]

return -> returns ?

+     *  ensure this function return 'true' or else the GrBackendObject will be invalid
+     *

[robertphillips, 2015/07/06 15:29:02]

On -> In ?

+     *  On OpenGL this will return the FramebufferObject ID.
+     */
+    bool getRenderTargetHandle(GrBackendObject*, BackendHandleAccess);
 
     /**
      *  Return a canvas that will draw into this surface. This will always
      *  return the same canvas for a given surface, and is manged/owned by the
      *  surface. It should not be used when its parent surface has gone out of
      *  scope.
      */
     SkCanvas* getCanvas();
 
     /**
@@ skipping 76 matching lines @@
 private:
     const SkSurfaceProps fProps;
     const int            fWidth;
     const int            fHeight;
     uint32_t             fGenerationID;
 
     typedef SkRefCnt INHERITED;
 };
 
 #endif