Refactor SkFontHost_linux into SkFontMgr_custom.

include/ports/SkFontMgr_custom.h

Index: include/ports/SkFontMgr_custom.h
diff --git a/include/ports/SkFontMgr_custom.h b/include/ports/SkFontMgr_custom.h
new file mode 100644
index 0000000000000000000000000000000000000000..ad37686ebb7918d3b43c081284e3a423eae710ab
--- /dev/null
+++ b/include/ports/SkFontMgr_custom.h
@@ -0,0 +1,18 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkFontMgr_custom_DEFINED
+#define SkFontMgr_custom_DEFINED
+
+#include "SkTypes.h"
+
+class SkFontMgr;
+
+/** Create a custom font manager which scans a given directory for font files. */
+SK_API SkFontMgr* SkFontMgr_New_Custom_Directory(const char* dir);
+
+#endif // SkFontMgr_custom_DEFINED