Add a function to convert a texture backed SkImage to raster.

include/core/SkImage.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 SkImage_DEFINED
 #define SkImage_DEFINED
 
@@ skipping 312 matching lines @@
     sk_sp<SkImage> makeSubset(const SkIRect& subset) const;
 
     /**
      *  Ensures that an image is backed by a texture (when GrContext is non-null). If no
      *  transformation is required, the returned image may be the same as this image. If the this
      *  image is from a different GrContext, this will fail.
      */
     sk_sp<SkImage> makeTextureImage(GrContext*) const;
 
     /**
+     * If the image is texture-backed this will make a raster copy of it (or nullptr if reading back
+     * the pixels fails). Otherwise, it returns the original image.
+     */
+    sk_sp<SkImage> makeNonTextureImage() const;
+    /**
      *  Apply a given image filter to this image, and return the filtered result.
      *
      *  The subset represents the active portion of this image. The return value is similarly an
      *  SkImage, with an active subset (outSubset). This is usually used with texture-backed
      *  images, where the texture may be approx-match and thus larger than the required size.
      *
      *  clipBounds constrains the device-space extent of the image which may be produced to the
      *  given rect.
      *
      *  offset is the amount to translate the resulting image relative to the src when it is drawn.
@@ skipping 119 matching lines @@
                                                 SkBudgeted);
 
     const int       fWidth;
     const int       fHeight;
     const uint32_t  fUniqueID;
 
     typedef SkRefCnt INHERITED;
 };
 
 #endif