Improve and unify Mac OS X run-time version checks

content/browser/renderer_host/backing_store_mac.mm

 // Copyright (c) 2011 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.
 
 #import <Cocoa/Cocoa.h>
 
 #include "content/browser/renderer_host/backing_store_mac.h"
 
 #include "base/logging.h"
 #include "base/mac/mac_util.h"
 #include "base/mac/scoped_cftyperef.h"
-#include "base/sys_info.h"
 #include "content/browser/renderer_host/render_process_host.h"
 #include "content/browser/renderer_host/render_widget_host.h"
 #include "content/browser/renderer_host/render_widget_host_view.h"
 #include "skia/ext/platform_canvas.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/surface/transport_dib.h"
 
 // Mac Backing Stores:
 //
 // Since backing stores are only ever written to or drawn into windows, we keep
 // our backing store in a CGLayer that can get cached in GPU memory.  This
 // allows acclerated drawing into the layer and lets scrolling and such happen
 // all or mostly on the GPU, which is good for performance.
 
 namespace {
 
 // Returns whether this version of OS X has broken CGLayers, see
 // http://crbug.com/45553 , comments 5 and 6.
 bool NeedsLayerWorkaround() {
-  int32 os_major, os_minor, os_bugfix;
-  base::SysInfo::OperatingSystemVersionNumbers(
-      &os_major, &os_minor, &os_bugfix);
-  return os_major == 10 && os_minor == 5;
+  return base::mac::IsOSLeopard();
 }
 
 }  // namespace
 
 BackingStoreMac::BackingStoreMac(RenderWidgetHost* widget,
                                  const gfx::Size& size)
     : BackingStore(widget, size) {
   cg_layer_.reset(CreateCGLayer());
   if (!cg_layer_) {
     // The view isn't in a window yet.  Use a CGBitmapContext for now.
@@ skipping 185 matching lines @@
   CGContextRef context = CGBitmapContextCreate(NULL,
                                                size().width(), size().height(),
                                                8, size().width() * 4,
                                                base::mac::GetSystemColorSpace(),
                                                kCGImageAlphaPremultipliedFirst |
                                                    kCGBitmapByteOrder32Host);
   DCHECK(context);
 
   return context;
 }