Adding public API method on SkImage for extracting the GPU texture handle.

src/image/SkImage_Gpu.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkImage_Base.h"
 #include "SkImagePriv.h"
 #include "SkBitmap.h"
 #include "SkCanvas.h"
 #include "GrContext.h"
 #include "GrTexture.h"
 #include "SkGrPixelRef.h"
 
 class SkImage_Gpu : public SkImage_Base {
 public:
     SK_DECLARE_INST_COUNT(SkImage_Gpu)
 
     SkImage_Gpu(GrTexture*);
     virtual ~SkImage_Gpu();
 
     virtual void onDraw(SkCanvas*, SkScalar x, SkScalar y, const SkPaint*) SK_OVERRIDE;
+    virtual GrTexture* onGetTexture() SK_OVERRIDE;
 
     GrTexture* getTexture() { return fTexture; }
 
     void setTexture(GrTexture* texture);
 
 private:
     GrTexture*  fTexture;
     SkBitmap    fBitmap;
 
     typedef SkImage_Base INHERITED;
@@ skipping 15 matching lines @@
 
 SkImage_Gpu::~SkImage_Gpu() {
     SkSafeUnref(fTexture);
 }
 
 void SkImage_Gpu::onDraw(SkCanvas* canvas, SkScalar x, SkScalar y,
                          const SkPaint* paint) {
     canvas->drawBitmap(fBitmap, x, y, paint);
 }
 
+GrTexture* SkImage_Gpu::onGetTexture() {
+    return fTexture;
+}
+
 void SkImage_Gpu::setTexture(GrTexture* texture) {
 
     if (texture == fTexture) {
         return;
     }
 
     SkRefCnt_SafeAssign(fTexture, texture);
     fBitmap.setPixelRef(new SkGrPixelRef(texture))->unref();
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 SkImage* SkImage::NewTexture(GrTexture* texture) {
     if (NULL == texture) {
         return NULL;
     }
 
     return SkNEW_ARGS(SkImage_Gpu, (texture));
 }
 
 GrTexture* SkTextureImageGetTexture(SkImage* image) {
     return ((SkImage_Gpu*)image)->getTexture();
 }
 
 void SkTextureImageSetTexture(SkImage* image, GrTexture* texture) {
     ((SkImage_Gpu*)image)->setTexture(texture);
 }