Enable mash shelf tooltips.

ash/test/shelf_view_test_api.cc

Index: ash/test/shelf_view_test_api.cc
diff --git a/ash/test/shelf_view_test_api.cc b/ash/test/shelf_view_test_api.cc
index 1ab9dcbe074fa086993e4d81899a07f99ccc8800..780274eb64e9739cf8cb2224830aa8291f6d8181 100644
--- a/ash/test/shelf_view_test_api.cc
+++ b/ash/test/shelf_view_test_api.cc
@@ -101,6 +101,10 @@ OverflowBubble* ShelfViewTestAPI::overflow_bubble() {
   return shelf_view_->overflow_bubble_.get();
 }
 
+ShelfTooltipManager* ShelfViewTestAPI::tooltip_manager() {
+  return &shelf_view_->tooltip_;
+}
+
 gfx::Size ShelfViewTestAPI::GetPreferredSize() {
   return shelf_view_->GetPreferredSize();
 }