Implement support for loading font files from outside system directory

content/common/dwrite_font_proxy_messages.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.
 
 #include <stdint.h>
 
 #include <utility>
 #include <vector>
 
 #include "base/strings/string16.h"
 #include "content/common/content_export.h"
 #include "ipc/ipc_message_macros.h"
+#include "ipc/ipc_platform_file.h"
 
 #undef IPC_MESSAGE_EXPORT
 #define IPC_MESSAGE_EXPORT CONTENT_EXPORT
 #define IPC_MESSAGE_START DWriteFontProxyMsgStart
 
 #ifndef CONTENT_COMMON_DWRITE_FONT_PROXY_MESSAGES_H_
 #define CONTENT_COMMON_DWRITE_FONT_PROXY_MESSAGES_H_
 
 // The macros can't handle a complex template declaration, so we typedef it.
 typedef std::pair<base::string16, base::string16> DWriteStringPair;
@@ skipping 25 matching lines @@
 
 // Returns the list of locale and family name pairs for the font family at the
 // specified index.
 IPC_SYNC_MESSAGE_CONTROL1_1(
     DWriteFontProxyMsg_GetFamilyNames,
     uint32_t /* family_index */,
     std::vector<DWriteStringPair> /* out family_names */)
 
 // Returns the list of font file paths in the system font directory that contain
 // font data for the font family at the specified index.
-IPC_SYNC_MESSAGE_CONTROL1_1(DWriteFontProxyMsg_GetFontFiles,
-                            uint32_t /* family_index */,
-                            std::vector<base::string16> /* out file_paths */)
+IPC_SYNC_MESSAGE_CONTROL1_2(
+    DWriteFontProxyMsg_GetFontFiles,
+    uint32_t /* family_index */,
+    std::vector<base::string16> /* out file_paths */,
+    std::vector<IPC::PlatformFileForTransit> /* out file_handles*/)
 
 // Locates a font family that is able to render the specified text using the
 // specified style. If successful, the family_index and family_name will
 // indicate which family in the system font collection can render the requested
 // text and the mapped_length will indicate how many characters can be
 // rendered. If no font exists that can render the text, family_index will be
 // UINT32_MAX and mapped_length will indicate how many characters cannot be
 // rendered by any installed font.
 IPC_SYNC_MESSAGE_CONTROL5_1(DWriteFontProxyMsg_MapCharacters,
                             base::string16 /* text */,
                             DWriteFontStyle /* font_style */,
                             base::string16 /* locale_name */,
                             uint32_t /* reading_direction */,
                             base::string16 /* base_family_name - optional */,
                             MapCharactersResult /* out */)