add peekPixels to canvas

src/image/SkSurface.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 "SkSurface_Base.h"
 #include "SkImagePriv.h"
 #include "SkCanvas.h"
@@ skipping 103 matching lines @@
 }
 
 SkSurface* SkSurface::newSurface(const SkImageInfo& info) {
     return asSB(this)->onNewSurface(info);
 }
 
 void SkSurface::draw(SkCanvas* canvas, SkScalar x, SkScalar y,
                      const SkPaint* paint) {
     return asSB(this)->onDraw(canvas, x, y, paint);
 }
+
+const void* SkSurface::peekPixels(SkImageInfo* info, size_t* rowBytes) {
+    return this->getCanvas()->peekPixels(info, rowBytes);
+}
+