Use ChildThreadImpl::thread_safe_sender in font proxy if available

content/child/dwrite_font_proxy/dwrite_font_proxy_init_win.h

Index: content/child/dwrite_font_proxy/dwrite_font_proxy_init_win.h
diff --git a/content/child/dwrite_font_proxy/dwrite_font_proxy_init_win.h b/content/child/dwrite_font_proxy/dwrite_font_proxy_init_win.h
index 68f8b6dfa489133864d6495fdddc9a86e3cdf456..e346cb0168474b6d3095dd7f29f2a0fab8a0c80a 100644
--- a/content/child/dwrite_font_proxy/dwrite_font_proxy_init_win.h
+++ b/content/child/dwrite_font_proxy/dwrite_font_proxy_init_win.h
@@ -11,8 +11,10 @@
 
 namespace content {
 
-// Initializes the dwrite font proxy.
-CONTENT_EXPORT void InitializeDWriteFontProxy();
+// Initializes the dwrite font proxy, using the specified callback to obtain
+// the sender to be used for sending IPC messages to the browser process.
+CONTENT_EXPORT void InitializeDWriteFontProxy(
+    const base::Callback<IPC::Sender*(void)>& sender);
 
 // Uninitialize the dwrite font proxy. This is safe to call even if the proxy
 // has not been initialized. After this, calls to load fonts may fail.