[Refactor] Consolidate the logic for whether a widget can be activated.

ash/shelf/shelf_widget.cc

Index: ash/shelf/shelf_widget.cc
diff --git a/ash/shelf/shelf_widget.cc b/ash/shelf/shelf_widget.cc
index cf980d29c78017e2eb158b7125b28006ba506c8f..544bccb066477716a4ee71e9f2d0d44aeb4240fa 100644
--- a/ash/shelf/shelf_widget.cc
+++ b/ash/shelf/shelf_widget.cc
@@ -421,7 +421,7 @@ void ShelfWidget::DelegateView::SetDimmed(bool value) {
     views::Widget::InitParams params(
         views::Widget::InitParams::TYPE_WINDOW_FRAMELESS);
     params.opacity = views::Widget::InitParams::TRANSLUCENT_WINDOW;
-    params.can_activate = false;
+    params.activatable = views::Widget::InitParams::ACTIVATABLE_NO;
     params.accept_events = false;
     params.ownership = views::Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
     params.parent = shelf_->GetNativeView();