Refactoring ImageBuffer to decouple it from Canvas2DLayerBridge

Source/core/rendering/RenderThemeChromiumMac.mm

 /*
  * Copyright (C) 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Google, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 1066 matching lines @@
     trackInfo.bounds = IntRect(IntPoint(), inflatedRect.size());
     trackInfo.min = 0;
     trackInfo.max = numeric_limits<SInt32>::max();
     trackInfo.value = lround(renderProgress->position() * nextafter(trackInfo.max, 0));
     trackInfo.trackInfo.progress.phase = lround(renderProgress->animationProgress() * nextafter(progressAnimationNumFrames, 0));
     trackInfo.attributes = kThemeTrackHorizontal;
     trackInfo.enableState = isActive(renderObject) ? kThemeTrackActive : kThemeTrackInactive;
     trackInfo.reserved = 0;
     trackInfo.filler1 = 0;
 
-    OwnPtr<ImageBuffer> imageBuffer = ImageBuffer::create(inflatedRect.size(), 1);
+    OwnPtr<ImageBuffer> imageBuffer = ImageBuffer::create(inflatedRect.size());
     if (!imageBuffer)
         return true;
 
     ContextContainer cgContextContainer(imageBuffer->context());
     CGContextRef cgContext = cgContextContainer.context();
     HIThemeDrawTrack(&trackInfo, 0, cgContext, kHIThemeOrientationNormal);
 
     GraphicsContextStateSaver stateSaver(*paintInfo.context);
 
     if (!renderProgress->style()->isLeftToRightDirection()) {
@@ skipping 906 matching lines @@
 
 bool RenderThemeChromiumMac::shouldUseFallbackTheme(RenderStyle* style) const
 {
     ControlPart part = style->appearance();
     if (part == CheckboxPart || part == RadioPart)
         return style->effectiveZoom() != 1;
     return false;
 }
 
 } // namespace WebCore