Unify the three places that patch font loading for PDFium on Windows.

content/child/child_message_filter.h

 // Copyright 2013 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 CONTENT_CHILD_CROSS_MESSAGE_FILTER_H_
 #define CONTENT_CHILD_CROSS_MESSAGE_FILTER_H_
 
 #include "base/memory/ref_counted.h"
 #include "ipc/ipc_sender.h"
 
@@ skipping 33 matching lines @@
   // PostTask() returns true but OnMessageReceived() is never called on the
   // target thread.  By default this does nothing.
   virtual void OnStaleMessageReceived(const IPC::Message& msg) {}
 
  protected:
   ChildMessageFilter();
   ~ChildMessageFilter() override;
 
  private:
   class Internal;
-  friend class ChildThread;
+  friend class ChildThreadImpl;
   friend class RenderThreadImpl;
   friend class WorkerThread;
 
   friend class base::RefCountedThreadSafe<ChildMessageFilter>;
 
   IPC::MessageFilter* GetFilter();
 
   // This implements IPC::MessageFilter to hide the actual filter methods from
   // child classes.
   Internal* internal_;
 
   scoped_refptr<ThreadSafeSender> thread_safe_sender_;
 
   DISALLOW_COPY_AND_ASSIGN(ChildMessageFilter);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_CROSS_MESSAGE_FILTER_H_