Add skia::RefPtr class to wrap ref counted classes from Skia.

ui/gfx/canvas_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.
 
 #import <Cocoa/Cocoa.h>
 
 #include "ui/gfx/canvas.h"
 
 #include "base/logging.h"
 #include "base/sys_string_conversions.h"
@@ skipping 41 matching lines @@
 }
 
 void Canvas::DrawStringWithShadows(const string16& text,
                                    const gfx::Font& font,
                                    SkColor color,
                                    const gfx::Rect& text_bounds,
                                    int flags,
                                    const ShadowValues& shadows) {
   DLOG_IF(WARNING, !shadows.empty()) << "Text shadow not implemented.";
 
-  SkTypeface* typeface = SkTypeface::CreateFromName(font.GetFontName().c_str(),
-                                                    FontTypefaceStyle(font));
+  skia::RefPtr<SkTypeface> typeface = SkTypeface::CreateFromName(
+      font.GetFontName().c_str(), FontTypefaceStyle(font));
   SkPaint paint;
-  paint.setTypeface(typeface);
-  typeface->unref();
+  paint.setTypeface(typeface.get());
   paint.setColor(color);
   canvas_->drawText(text.c_str(),
                     text.size() * sizeof(string16::value_type),
                     text_bounds.x(),
                     text_bounds.bottom(),
                     paint);
 }
 
 void Canvas::DrawStringWithHalo(const string16& text,
                                 const gfx::Font& font,
                                 SkColor text_color,
                                 SkColor halo_color,
                                 int x, int y, int w, int h,
                                 int flags) {
 }
 
 }  // namespace gfx