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

content/child/thread_safe_sender.h

Index: content/child/thread_safe_sender.h
diff --git a/content/child/thread_safe_sender.h b/content/child/thread_safe_sender.h
index 443e20a720a3893fd3826f1a44945be9e8019c9c..37ad96bfbf4ed8b16c1b13dd36f43fc546fa05fd 100644
--- a/content/child/thread_safe_sender.h
+++ b/content/child/thread_safe_sender.h
@@ -19,9 +19,9 @@ class SyncMessageFilter;
 }
 
 namespace content {
-class ChildThread;
+class ChildThreadImpl;
 
-// The class of Sender returned by ChildThread::thread_safe_sender().
+// The class of Sender returned by ChildThreadImpl::thread_safe_sender().
 class CONTENT_EXPORT ThreadSafeSender
     : public IPC::Sender,
       public base::RefCountedThreadSafe<ThreadSafeSender> {
@@ -29,7 +29,7 @@ class CONTENT_EXPORT ThreadSafeSender
   bool Send(IPC::Message* msg) override;
 
  private:
-  friend class ChildThread;  // for construction
+  friend class ChildThreadImpl;  // for construction
   friend class IndexedDBDispatcherTest;
   friend class WebIDBCursorImplTest;
   friend class base::RefCountedThreadSafe<ThreadSafeSender>;