Create direct write font proxy classes and unit tests.

content/child/dwrite_font_proxy/dwrite_font_proxy_init_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_INIT_WIN_H_
+#define CONTENT_CHILD_DWRITE_FONT_PROXY_DWRITE_FONT_PROXY_INIT_WIN_H_
+
+#include "base/callback.h"
+#include "content/common/content_export.h"
+#include "ipc/ipc_sender.h"
+
+namespace content {
+
+// Initializes the dwrite font proxy, using the specified callback to obtain
+// the sender to be used for sending IPC messages to the browser process.
+void CONTENT_EXPORT

[scottmg, 2015/11/13 00:51:46]

The CONTENT_EXPORTs go before void.

[Ilya Kulshin, 2015/11/14 00:25:33]

Done.

+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.
+void CONTENT_EXPORT UninitializeDWriteFontProxy();
+
+// Configures the dwrite font proxy to use the specified sender. This can be
+// useful in tests which use a fake render thread which is unable to process
+// font IPC messages. This should only be called when running as a test.
+void CONTENT_EXPORT SetDWriteFontProxySenderForTesting(IPC::Sender* sender);
+
+}  // namespace content
+
+#endif  // CONTENT_CHILD_DWRITE_FONT_PROXY_DWRITE_FONT_PROXY_INIT_WIN_H_