events: Update mouse-event handlers to not return EventResult.

ash/wm/app_list_controller.cc

Index: ash/wm/app_list_controller.cc
diff --git a/ash/wm/app_list_controller.cc b/ash/wm/app_list_controller.cc
index bcc85e5594946d5711cc4e6dffd7b783edf9f2fa..2bfbd9675be610f91cb73cece7c2056c67c3bd08 100644
--- a/ash/wm/app_list_controller.cc
+++ b/ash/wm/app_list_controller.cc
@@ -231,10 +231,9 @@ void AppListController::UpdateBounds() {
 ////////////////////////////////////////////////////////////////////////////////
 // AppListController, aura::EventFilter implementation:
 
-ui::EventResult AppListController::OnMouseEvent(ui::MouseEvent* event) {
+void AppListController::OnMouseEvent(ui::MouseEvent* event) {
   if (event->type() == ui::ET_MOUSE_PRESSED)
     ProcessLocatedEvent(event);
-  return ui::ER_UNHANDLED;
 }
 
 void AppListController::OnGestureEvent(ui::GestureEvent* event) {