Linux: plumb fontconfig call out to the sandbox host.

base/message_pump_glib.cc

Index: base/message_pump_glib.cc
diff --git a/base/message_pump_glib.cc b/base/message_pump_glib.cc
index ac0a0800979b7b71fdcf89384790abac99aa1504..7910a95a1ef39fe3deb62ac46fd2e56f39f8410e 100644
--- a/base/message_pump_glib.cc
+++ b/base/message_pump_glib.cc
@@ -267,10 +267,12 @@ void MessagePumpForUI::HandleDispatch() {
 }
 
 void MessagePumpForUI::AddObserver(Observer* observer) {
+  LOG(ERROR) << "AddObserver";
   observers_.AddObserver(observer);
 }
 
 void MessagePumpForUI::RemoveObserver(Observer* observer) {
+  LOG(ERROR) << "RemoveObserver";
   observers_.RemoveObserver(observer);
 }