Fix Google3 fonts. Use fontconfig rather than custom_directory_factory. Add Google3 font caching.

Some future dependents require these changes.

Depends on internal cl/108287941.

Review URL: https://codereview.chromium.org/1471033002
diff --git a/tools/BUILD_simulator.py b/tools/BUILD_simulator.py
index 3c0ed61..efed6fa 100755
--- a/tools/BUILD_simulator.py
+++ b/tools/BUILD_simulator.py
@@ -84,6 +84,7 @@
   'CONDITION_IOS': 'CONDITION_IOS',
   'DM_EXTERNAL_DEPS': [],
   'EXTERNAL_DEPS_ALL': [],
+  'EXTERNAL_INCLUDES': [],
 }
 local_names = {}
 execfile('BUILD.public', global_names, local_names)