add ability to get FBO ID to Surface

include/gpu/GrRenderTarget.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrRenderTarget_DEFINED
 #define GrRenderTarget_DEFINED
 
@@ skipping 120 matching lines @@
     // a MSAA RT may require explicit resolving , it may auto-resolve (e.g. FBO
     // 0 in GL), or be unresolvable because the client didn't give us the
     // resolve destination.
     enum ResolveType {
         kCanResolve_ResolveType,
         kAutoResolves_ResolveType,
         kCantResolve_ResolveType,
     };
     virtual ResolveType getResolveType() const = 0;
 
+    /**
+     *  Return the native ID or handle to the rendertarget, depending on the
+     *  platform. e.g. on OpenGL, return the FBO ID.
+     */
+    virtual GrBackendObject getRenderTargetHandle() const = 0;
+
     // Provides access to functions that aren't part of the public API.
     GrRenderTargetPriv renderTargetPriv();
     const GrRenderTargetPriv renderTargetPriv() const;
 
 protected:
     GrRenderTarget(GrGpu* gpu, LifeCycle lifeCycle, const GrSurfaceDesc& desc,
                    SampleConfig sampleConfig)
         : INHERITED(gpu, lifeCycle, desc)
         , fStencilAttachment(NULL)
         , fSampleConfig(sampleConfig) {
@@ skipping 13 matching lines @@
     GrStencilAttachment*  fStencilAttachment;
     SampleConfig          fSampleConfig;
 
     SkIRect               fResolveRect;
 
     typedef GrSurface INHERITED;
 };
 
 
 #endif