move remaining virtual draw methods to onDraw

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
 
 #include "SkImageInfo.h"
 #include "SkImageEncoder.h"
 #include "SkRefCnt.h"
 #include "SkScalar.h"
 #include "SkShader.h"
 
 class SkData;
 class SkCanvas;
 class SkImageGenerator;
 class SkPaint;
+class SkString;
 class SkSurface;
 class SkSurfaceProps;
 class GrContext;
 class GrTexture;
 
 /**
  *  SkImage is an abstraction for drawing a rectagle of pixels, though the
  *  particular type of image could be actually storing its data on the GPU, or
  *  as drawing commands (picture or PDF or otherwise), ready to be played back
  *  into another canvas.
@@ skipping 126 matching lines @@
      *  Draw the image, cropped to the src rect, to the dst rect of a canvas.
      *  If src is larger than the bounds of the image, the rest of the image is
      *  filled with transparent black pixels.
      *
      *  See SkCanvas::drawBitmapRectToRect for similar behavior.
      */
     void drawRect(SkCanvas*, const SkRect* src, const SkRect& dst, const SkPaint*) const;
 };
 
 #endif