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

include/core/SkImage.h

Index: include/core/SkImage.h
===================================================================
--- include/core/SkImage.h	(revision 8915)
+++ include/core/SkImage.h	(working copy)
@@ -72,6 +72,13 @@
     int height() const { return fHeight; }
     uint32_t uniqueID() const { return fUniqueID; }
 
+    /**
+     * Return the GrTexture that stores the image pixels. Calling getTexture
+     * does not affect the reference count of the GrTexture object.
+     * Will return NULL if the image does not use a texture.
+     */
+    GrTexture* getTexture();
+
     SkShader*   newShaderClamp() const;
     SkShader*   newShader(SkShader::TileMode, SkShader::TileMode) const;