ui/gfx: Make gfx::Canvas inherit from gfx::CanvasSkia.

ui/views/controls/button/text_button.cc

 // 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/views/controls/button/text_button.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "grit/ui_resources.h"
@@ skipping 498 matching lines @@
     SkColor text_color = (show_multiple_icon_states_ &&
         (state() == BS_HOT || state() == BS_PUSHED)) ? color_hover_ : color_;
 
     int draw_string_flags = gfx::CanvasSkia::DefaultCanvasTextAlignment() |
         ComputeCanvasStringFlags();
 
     if (mode == PB_FOR_DRAG) {
 #if defined(OS_WIN)
       // TODO(erg): Either port DrawStringWithHalo to linux or find an
       // alternative here.
-      canvas->AsCanvasSkia()->DrawStringWithHalo(
+      canvas->DrawStringWithHalo(
           text_, font_, text_color, color_highlight_, text_bounds.x(),
           text_bounds.y(), text_bounds.width(), text_bounds.height(),
           draw_string_flags);
 #else
       canvas->DrawStringInt(text_,
                             font_,
                             text_color,
                             text_bounds.x(),
                             text_bounds.y(),
                             text_bounds.width(),
                             text_bounds.height(),
                             draw_string_flags);
 #endif
     } else if (has_text_halo_) {
-      canvas->AsCanvasSkia()->DrawStringWithHalo(
+      canvas->DrawStringWithHalo(
           text_, font_, text_color, text_halo_color_,
           text_bounds.x(), text_bounds.y(), text_bounds.width(),
           text_bounds.height(), draw_string_flags);
     } else if (has_shadow_) {
       SkColor shadow_color =
           GetWidget()->IsActive() ? active_text_shadow_color_ :
                                     inactive_text_shadow_color_;
       canvas->DrawStringInt(text_,
                             font_,
                             shadow_color,
@@ skipping 289 matching lines @@
 #endif
 }
 
 void NativeTextButton::GetExtraParams(
     gfx::NativeTheme::ExtraParams* params) const {
   TextButton::GetExtraParams(params);
   params->button.has_border = true;
 }
 
 }  // namespace views