Use ChildThreadImpl::thread_safe_sender in font proxy if available

content/child/dwrite_font_proxy/dwrite_font_proxy_win.h

 // Copyright 2015 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_DWRITE_FONT_PROXY_DWRITE_FONT_PROXY_WIN_H_
 #define CONTENT_CHILD_DWRITE_FONT_PROXY_DWRITE_FONT_PROXY_WIN_H_
 
 #include <dwrite.h>
 #include <wrl.h>
 
@@ skipping 46 matching lines @@
       UINT32 collection_key_size,
       IDWriteFontFileEnumerator** font_file_enumerator) override;
 
   // IDWriteFontFileLoader:
   HRESULT STDMETHODCALLTYPE
   CreateStreamFromKey(const void* font_file_reference_key,
                       UINT32 font_file_reference_key_size,
                       IDWriteFontFileStream** font_file_stream) override;
 
   HRESULT STDMETHODCALLTYPE
-  RuntimeClassInitialize(IDWriteFactory* factory, IPC::Sender* sender_override);
+  RuntimeClassInitialize(IDWriteFactory* factory,
+                         const base::Callback<IPC::Sender*(void)>& sender);
 
   void Unregister();
 
   bool LoadFamily(UINT32 family_index,
                   IDWriteFontCollection** containing_collection);
 
   // Gets the family at the specified index with the expected name. This can be
   // used to avoid an IPC call when both the index and family name are known.
   bool GetFontFamily(UINT32 family_index,
                      const base::string16& family_name,
                      IDWriteFontFamily** font_family);
 
   bool LoadFamilyNames(UINT32 family_index, IDWriteLocalizedStrings** strings);
 
   bool CreateFamily(UINT32 family_index);
 
  private:
-  IPC::Sender* GetSender();
-
   Microsoft::WRL::ComPtr<IDWriteFactory> factory_;
   std::vector<Microsoft::WRL::ComPtr<DWriteFontFamilyProxy>> families_;
   std::map<base::string16, UINT32> family_names_;
   UINT32 family_count_ = UINT_MAX;
-  IPC::Sender* sender_override_;
+  base::Callback<IPC::Sender*(void)> sender_;
 
   DISALLOW_ASSIGN(DWriteFontCollectionProxy);
 };
 
 // Implements the DirectWrite font family interface. This class is just a
 // stub, until something calls a method that requires actual font data. At that
 // point this will load the font files into a custom collection and
 // subsequently calls will be proxied to the resulting DirectWrite object.
 class CONTENT_EXPORT DWriteFontFamilyProxy
     : public Microsoft::WRL::RuntimeClass<
@@ skipping 97 matching lines @@
   HRESULT STDMETHODCALLTYPE RuntimeClassInitialize(HANDLE handle);
 
  private:
   base::MemoryMappedFile data_;
 
   DISALLOW_ASSIGN(FontFileStream);
 };
 
 }  // namespace content
 #endif  // CONTENT_CHILD_DWRITE_FONT_PROXY_DWRITE_FONT_PROXY_WIN_H_