Create direct write font proxy classes and unit tests.

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 <utility>
+#include <vector>
+
+#include "base/strings/string16.h"
+#include "content/common/content_export.h"
+#include "ipc/ipc_message_macros.h"
+
+#undef IPC_MESSAGE_EXPORT
+#define IPC_MESSAGE_EXPORT CONTENT_EXPORT
+#define IPC_MESSAGE_START DWriteFontProxyMsgStart
+
+// The macros can't handle a complex template declaration, so we typedef it.
+typedef std::pair<base::string16, base::string16> StringPair;

[Alexei Svitkine (slow), 2015/11/25 20:17:45]

Nit: Please name this type more specifically, e.g. DWriteStringPair.

Otherwise, you're polluting the global namespace with this generic named type.

[Ilya Kulshin, 2015/12/02 02:23:02]

Done.

+
+// Locates the index of the specified font family within the system collection.
+IPC_SYNC_MESSAGE_CONTROL1_1(DWriteFontProxyMsg_FindFamily,
+                            base::string16 /* family_name */,
+                            uint32_t /* out index */)
+
+// Returns the number of font families in the system collection.
+IPC_SYNC_MESSAGE_CONTROL0_1(DWriteFontProxyMsg_GetFamilyCount,
+                            uint32_t /* out count */)
+
+// 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<StringPair> /* 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 */)