Move |PlatformFont::GetStringWidth()| implementation up into font.cc directly.

ui/gfx/platform_font_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.
 
 #include "ui/gfx/platform_font_mac.h"
 
 #include <Cocoa/Cocoa.h>
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_nsobject.h"
 #include "base/sys_string_conversions.h"
 #include "base/utf_string_conversions.h"
-#include "ui/gfx/canvas_skia.h"
 #include "ui/gfx/font.h"
 
 namespace gfx {
 
 ////////////////////////////////////////////////////////////////////////////////
 // PlatformFontMac, public:
 
 PlatformFontMac::PlatformFontMac() {
   font_size_ = [NSFont systemFontSize];
   style_ = gfx::Font::NORMAL;
@@ skipping 25 matching lines @@
 }
 
 int PlatformFontMac::GetBaseline() const {
   return ascent_;
 }
 
 int PlatformFontMac::GetAverageCharacterWidth() const {
   return average_width_;
 }
 
-int PlatformFontMac::GetStringWidth(const string16& text) const {
-  int width = 0, height = 0;
-  CanvasSkia::SizeStringInt(text, Font(const_cast<PlatformFontMac*>(this)),
-                            &width, &height, gfx::Canvas::NO_ELLIPSIS);
-  return width;
-}
-
 int PlatformFontMac::GetExpectedTextWidth(int length) const {
   return length * average_width_;
 }
 
 int PlatformFontMac::GetStyle() const {
   return style_;
 }
 
 std::string PlatformFontMac::GetFontName() const {
   return font_name_;
@@ skipping 58 matching lines @@
 }
 
 // static
 PlatformFont* PlatformFont::CreateFromNameAndSize(const std::string& font_name,
                                                   int font_size) {
   return new PlatformFontMac(font_name, font_size);
 }
 
 }  // namespace gfx