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

ui/views/examples/text_example.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/examples/text_example.h"
 
 #include "base/utf_string_conversions.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/canvas_skia.h"
@@ skipping 88 matching lines @@
       fade_(false),
       fade_mode_(gfx::CanvasSkia::TruncateFadeTail) {
   }
 
   virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE {
 #if defined(OS_WIN)
     if (fade_) {
       gfx::Rect rect(0, 0, width(), height());
       size_t characters_to_truncate_from_head =
           gfx::CanvasSkia::TruncateFadeHeadAndTail ? 10 : 0;
-      canvas->AsCanvasSkia()->DrawFadeTruncatingString(text_, fade_mode_,
+      canvas->DrawFadeTruncatingString(text_, fade_mode_,
           characters_to_truncate_from_head, font_, SK_ColorDKGRAY, rect);
       return;
     }
 #endif
 
     if (halo_) {
-      canvas->AsCanvasSkia()->DrawStringWithHalo(text_, font_, SK_ColorDKGRAY,
+      canvas->DrawStringWithHalo(text_, font_, SK_ColorDKGRAY,
           SK_ColorWHITE, 0, 0, width(), height(), text_flags_);
     } else {
       canvas->DrawStringInt(text_, font_, SK_ColorDKGRAY, 0, 0, width(),
           height(), text_flags_);
     }
   }
 
   int text_flags() const { return text_flags_; }
   void set_text_flags(int text_flags) { text_flags_ = text_flags; }
 
@@ skipping 237 matching lines @@
         text_flags |= gfx::Canvas::HIDE_PREFIX;
         break;
     }
   }
   text_view_->set_text_flags(text_flags);
   text_view_->SchedulePaint();
 }
 
 }  // namespace examples
 }  // namespace views