Fix shelf auto-hide calculation for app-list visibility.

ash/common/shelf/app_list_button.cc

Index: ash/common/shelf/app_list_button.cc
diff --git a/ash/common/shelf/app_list_button.cc b/ash/common/shelf/app_list_button.cc
index e3bdf2235a90325706f67cd8ea8629f517d3f534..59f72b4bbe9b9021dc4e2b4a057fc234a6ab915f 100644
--- a/ash/common/shelf/app_list_button.cc
+++ b/ash/common/shelf/app_list_button.cc
@@ -33,8 +33,6 @@ AppListButton::AppListButton(InkDropButtonListener* listener,
                              ShelfView* shelf_view,
                              WmShelf* wm_shelf)
     : views::ImageButton(nullptr),
-      draw_background_as_active_(false),
-      background_alpha_(0),
       listener_(listener),
       shelf_view_(shelf_view),
       wm_shelf_(wm_shelf) {
@@ -62,6 +60,8 @@ void AppListButton::OnAppListShown() {
     AnimateInkDrop(views::InkDropState::ACTIVATED, nullptr);
   else
     SchedulePaint();
+  is_showing_app_list_ = true;
+  wm_shelf_->UpdateAutoHideState();
 }
 
 void AppListButton::OnAppListDismissed() {
@@ -69,6 +69,8 @@ void AppListButton::OnAppListDismissed() {
     AnimateInkDrop(views::InkDropState::DEACTIVATED, nullptr);
   else
     SchedulePaint();
+  is_showing_app_list_ = false;
+  wm_shelf_->UpdateAutoHideState();
 }
 
 void AppListButton::SetBackgroundAlpha(int alpha) {