Linux: plumb fontconfig call out to the sandbox host.

chrome/renderer/renderer_sandbox_support_linux.h

+// Copyright (c) 2009 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 CHROME_RENDERER_RENDERER_SANDBOX_SUPPORT_H_
+#define CHROME_RENDERER_RENDERER_SANDBOX_SUPPORT_H_
+
+#include <stdint.h>
+
+#include <string>
+
+namespace renderer_sandbox_support {
+
+// Return a font family which provides glyphs for the Unicode code points
+// specified by |utf16|
+//   utf16: a native-endian UTF16 string
+//   num_utf16: the number of 16-bit words in |utf16|
+//
+// Returns: the font family or an empty string if the request could not be
+// satisfied.
+std::string getFontFamilyForCharacters(const uint16_t* utf16, size_t num_utf16);
+
+};  // namespace render_sandbox_support
+
+#endif  // CHROME_RENDERER_RENDER_SANDBOX_SUPPORT_H_