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

src/image/SkImage.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"
@@ skipping 13 matching lines @@
     do {
         id = sk_atomic_inc(&gUniqueID) + 1;
     } while (0 == id);
     return id;
 }
 
 void SkImage::draw(SkCanvas* canvas, SkScalar x, SkScalar y,
                    const SkPaint* paint) {
     asIB(this)->onDraw(canvas, x, y, paint);
 }
+
+GrTexture* SkImage::getTexture() {
+    return asIB(this)->onGetTexture();
+}
+