Make ui_controls only usable from interactive_ui_tests. This has two benefits:

chrome/test/base/interactive_test_utils.cc

Index: chrome/test/base/interactive_test_utils.cc
===================================================================
--- chrome/test/base/interactive_test_utils.cc	(revision 176470)
+++ chrome/test/base/interactive_test_utils.cc	(working copy)
@@ -101,5 +101,17 @@
   return !testing::Test::HasFatalFailure();
 }
 
+namespace internal {
 
+void ClickTask(ui_controls::MouseButton button,
+               int state,
+               const base::Closure& followup) {
+  if (!followup.is_null())
+    ui_controls::SendMouseEventsNotifyWhenDone(button, state, followup);
+  else
+    ui_controls::SendMouseEvents(button, state);
+}
+
+}  // namespace internal
+
 }  // namespace ui_test_utils