Remove uses of skia::ReadPixels(PaintCanvas)

ui/gfx/canvas.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GFX_CANVAS_H_
 #define UI_GFX_CANVAS_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 453 matching lines @@
   // Apply transformation on the canvas.
   void Transform(const Transform& transform);
 
   // Draws the given string with a fade gradient at the end.
   void DrawFadedString(const base::string16& text,
                        const FontList& font_list,
                        SkColor color,
                        const Rect& display_rect,
                        int flags);
 
+  SkBitmap ToBitmap();
+
   // TODO(enne): rename sk_canvas members and interface.
   cc::PaintCanvas* sk_canvas() { return canvas_; }
   float image_scale() const { return image_scale_; }
 
  private:
   // Tests whether the provided rectangle intersects the current clip rect.
   bool IntersectsClipRect(const SkRect& rect);
 
   // Helper for the DrawImageInt functions declared above. The
   // |remove_image_scale| parameter indicates if the scale of the |image_rep|
@@ skipping 22 matching lines @@
   // but surface_ will be null.
   sk_sp<cc::PaintSurface> surface_;
   cc::PaintCanvas* canvas_;
 
   DISALLOW_COPY_AND_ASSIGN(Canvas);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_CANVAS_H_