Simplify platform_canvas.h by recognizing that PlatformCanvas does not actually extend

ppapi/shared_impl/private/ppb_browser_font_trusted_shared.h

 // 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.
 
 #ifndef PPAPI_SHARED_IMPL_PRIVATE_PPB_BROWSER_FONT_TRUSTED_SHARED_H_
 #define PPAPI_SHARED_IMPL_PRIVATE_PPB_BROWSER_FONT_TRUSTED_SHARED_H_
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "ppapi/c/pp_bool.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/c/pp_resource.h"
 #include "ppapi/c/pp_stdint.h"
 #include "ppapi/shared_impl/ppapi_preferences.h"
 #include "ppapi/shared_impl/ppapi_shared_export.h"
 #include "ppapi/shared_impl/resource.h"
 #include "ppapi/thunk/ppb_browser_font_trusted_api.h"
 
-namespace skia {
-class PlatformCanvas;
-}
+class SkCanvas;
 
 namespace WebKit {
 class WebFont;
 }
 
 namespace ppapi {
 
 class PPAPI_SHARED_EXPORT PPB_BrowserFont_Trusted_Shared
     : public Resource,
       public thunk::PPB_BrowserFont_Trusted_API {
@@ skipping 32 matching lines @@
       const PP_BrowserFont_Trusted_TextRun* text,
       uint32_t char_offset) OVERRIDE;
 
  private:
   PPB_BrowserFont_Trusted_Shared(ResourceObjectType type,
                                  PP_Instance instance,
                                  const PP_BrowserFont_Trusted_Description& desc,
                                  const Preferences& prefs);
 
   // Internal version of DrawTextAt that takes a mapped PlatformCanvas.
-  void DrawTextToCanvas(skia::PlatformCanvas* destination,
+  void DrawTextToCanvas(SkCanvas* destination,
                         const PP_BrowserFont_Trusted_TextRun& text,
                         const PP_Point* position,
                         uint32_t color,
                         const PP_Rect* clip,
                         PP_Bool image_data_is_opaque);
 
   scoped_ptr<WebKit::WebFont> font_;
 
   DISALLOW_COPY_AND_ASSIGN(PPB_BrowserFont_Trusted_Shared);
 };
 
 }  // namespace ppapi
 
 #endif  // PPAPI_SHARED_IMPL_PRIVATE_PPB_BROWSER_FONT_TRUSTED_SHARED_H_