Make sure ppapi::WebKitForwarding::Font is deleted on the WebKit thread.

ppapi/proxy/ppb_font_proxy.h

 // 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.
 
 #ifndef PPAPI_PROXY_PPB_FONT_PROXY_H_
 #define PPAPI_PROXY_PPB_FONT_PROXY_H_
 
 #include "base/basictypes.h"
 #include "base/synchronization/waitable_event.h"
 #include "ppapi/proxy/host_resource.h"
@@ skipping 57 matching lines @@
                              uint32_t color,
                              const PP_Rect* clip,
                              PP_Bool image_data_is_opaque) OVERRIDE;
   virtual int32_t MeasureText(const PP_TextRun_Dev* text) OVERRIDE;
   virtual uint32_t CharacterOffsetForPixel(const PP_TextRun_Dev* text,
                                            int32_t pixel_position) OVERRIDE;
   virtual int32_t PixelOffsetForCharacter(const PP_TextRun_Dev* text,
                                           uint32_t char_offset) OVERRIDE;
 
  private:
-  // Posts the given closure to the WebKit thread and waits on the
-  // webkit_event_ for the task to continue.
-  void RunOnWebKitThread(const base::Closure& task);
+  // Posts the given closure to the WebKit thread.
+  // If |blocking| is true, the method waits on |webkit_event_| for the task to
+  // continue.
+  void RunOnWebKitThread(bool blocking, const base::Closure& task);
+
+  static void DeleteFontForwarding(
+      ppapi::WebKitForwarding::Font* font_forwarding);
 
   base::WaitableEvent webkit_event_;
 
-  scoped_ptr<ppapi::WebKitForwarding::Font> font_forwarding_;
+  // This class owns |font_forwarding_|.
+  // |font_forwarding_| should always be used on the WebKit thread (including
+  // destruction).
+  ppapi::WebKitForwarding::Font* font_forwarding_;
 
   DISALLOW_COPY_AND_ASSIGN(Font);
 };
 
 }  // namespace proxy
 }  // namespace pp
 
 #endif  // PPAPI_PROXY_PPB_FONT_PROXY_H_