use new readPixels, as old version using Config8888 is deprecated

Source/platform/graphics/GraphicsContext.cpp

 /*
  * Copyright (C) 2003, 2004, 2005, 2006, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 392 matching lines @@
 void GraphicsContext::setColorFilter(ColorFilter colorFilter)
 {
     GraphicsContextState* stateToSet = mutableState();
 
     // We only support one active color filter at the moment. If (when) this becomes a problem,
     // we should switch to using color filter chains (Skia work in progress).
     ASSERT(!stateToSet->colorFilter());
     stateToSet->setColorFilter(WebCoreColorFilterToSkiaColorFilter(colorFilter));
 }
 
-bool GraphicsContext::readPixels(SkBitmap* bitmap, int x, int y, SkCanvas::Config8888 config8888)
+bool GraphicsContext::readPixels(const SkImageInfo& info, void* pixels, size_t rowBytes, int x, int y)
 {
     if (paintingDisabled())
         return false;
 
-    return m_canvas->readPixels(bitmap, x, y, config8888);
+    return m_canvas->readPixels(info, pixels, rowBytes, x, y);
 }
 
 void GraphicsContext::setMatrix(const SkMatrix& matrix)
 {
     if (paintingDisabled())
         return;
 
     realizeCanvasSave(SkCanvas::kMatrix_SaveFlag);
 
     m_canvas->setMatrix(matrix);
@@ skipping 1456 matching lines @@
 
 void GraphicsContext::didDrawTextInRect(const SkRect& textRect)
 {
     if (m_trackTextRegion) {
         TRACE_EVENT0("skia", "PlatformContextSkia::trackTextRegion");
         m_textRegion.join(textRect);
     }
 }
 
 }