Remove PlatformCanvas::GetBitmapContext()

ui/gfx/canvas_paint_mac.mm

 // 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.
 
 #include "ui/gfx/canvas_paint_mac.h"
 #include "ui/gfx/geometry/size.h"
 
 namespace gfx {
 
 CanvasSkiaPaint::CanvasSkiaPaint(NSRect dirtyRect)
     : rectangle_(dirtyRect),
       composite_alpha_(false) {
   Init(true);
 }
 
 CanvasSkiaPaint::CanvasSkiaPaint(NSRect dirtyRect, bool opaque)
     : rectangle_(dirtyRect),
       composite_alpha_(false) {
   Init(opaque);
 }
 
 CanvasSkiaPaint::~CanvasSkiaPaint() {
   if (!is_empty()) {
     SkCanvas* canvas = sk_canvas();
     canvas->restoreToCount(1);
 
     // Blit the dirty rect to the current context.
+    skia::ScopedPlatformPaint spp(canvas);
     CGImageRef image =
-        CGBitmapContextCreateImage(skia::GetBitmapContext(*canvas));
+        CGBitmapContextCreateImage(spp.GetNativeDrawingContext());
     CGRect dest_rect = NSRectToCGRect(rectangle_);
 
     CGContextRef destination_context =
         (CGContextRef)[[NSGraphicsContext currentContext] graphicsPort];
     CGContextSaveGState(destination_context);
     CGContextSetBlendMode(
         destination_context,
         composite_alpha_ ? kCGBlendModeNormal : kCGBlendModeCopy);
 
     if ([[NSGraphicsContext currentContext] isFlipped]) {
@@ skipping 25 matching lines @@
 
     // Need to translate so that the dirty region appears at the origin of the
     // surface.
   canvas->translate(-SkDoubleToScalar(NSMinX(rectangle_)),
                     -SkDoubleToScalar(NSMinY(rectangle_)));
 }
 
 }  // namespace skia