Fix ContentsView::ResetForShow()

This clears the visibility of search results and assistant, while
the visibility of horizontal page container (i.e. apps grid)
remains. I thought SetActiveState() will update that, but actually
it does nothing if the target page is not visible. As the result,
this can cause nothing to be shown in the app-list.

BUG=b/142069648
TEST=manually, app_list_unittests

Change-Id: I6e50b7e1b2f2234bd347ac5b7fdef35ecbe8522d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1838303Reviewed-by: Tao Wu <wutao@chromium.org>
Reviewed-by: Alex Newcomer <newcomer@chromium.org>
Commit-Queue: Jun Mukai <mukai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#702647}

ash/app_list/views/app_list_view_unittest.cc

@@ -25,6 +25,7 @@
 #include "ash/app_list/views/contents_view.h"
 #include "ash/app_list/views/expand_arrow_view.h"
 #include "ash/app_list/views/folder_header_view.h"
+#include "ash/app_list/views/horizontal_page_container.h"
 #include "ash/app_list/views/page_switcher.h"
 #include "ash/app_list/views/result_selection_controller.h"
 #include "ash/app_list/views/search_box_view.h"
@@ -2649,6 +2650,30 @@ TEST_F(AppListViewFocusTest, ShowEmbeddedAssistantUI) {
   EXPECT_EQ(1, GetTotalOpenAssistantUICount());
 }
 
+// Tests that the correct contents is visible in the contents_view upon
+// reshowing. See b/142069648 for the details.
+TEST_F(AppListViewTest, AppsGridVisibilityOnResetForShow) {
+  base::test::ScopedFeatureList scoped_feature_list;
+  scoped_feature_list.InitWithFeatures(
+      {app_list_features::kEnableEmbeddedAssistantUI}, {});
+  Initialize(true /*is_tablet_mode*/);
+  Show(true /*is_tablet_mode*/);
+
+  contents_view()->ShowEmbeddedAssistantUI(true);
+  EXPECT_FALSE(contents_view()->horizontal_page_container()->GetVisible());
+  EXPECT_FALSE(contents_view()->search_results_page_view()->GetVisible());
+  const int assistant_page_index = contents_view()->GetPageIndexForState(
+      ash::AppListState::kStateEmbeddedAssistant);
+  EXPECT_TRUE(contents_view()->GetPageView(assistant_page_index)->GetVisible());
+
+  view_->OnTabletModeChanged(false);
+  Show(false /*is_tablet_mode*/);
+  EXPECT_TRUE(contents_view()->horizontal_page_container()->GetVisible());
+  EXPECT_FALSE(contents_view()->search_results_page_view()->GetVisible());
+  EXPECT_FALSE(
+      contents_view()->GetPageView(assistant_page_index)->GetVisible());
+}
+
 // Tests that no answer card view when kEnableEmbeddedAssistantUI is enabled.
 TEST_F(AppListViewTest, NoAnswerCardWhenEmbeddedAssistantUIEnabled) {
   base::test::ScopedFeatureList scoped_feature_list;

ash/app_list/views/contents_view.cc

@@ -152,11 +152,13 @@ void ContentsView::ResetForShow() {
   // QueryChanged(). Since it wants to reset to kStateApps, first reset the
   // search box and then set its active state to kStateApps.
   GetSearchBoxView()->ResetForShow();
-  SetActiveState(ash::AppListState::kStateApps, /*animate=*/false);
-  // Make other pages invisible.
+  // Make sure the default visibilities of the pages. This should be done before
+  // SetActiveState() since it checks the visibility of the pages.
+  horizontal_page_container_->SetVisible(true);
   search_results_page_view_->SetVisible(false);
   if (assistant_page_view_)
     assistant_page_view_->SetVisible(false);
+  SetActiveState(ash::AppListState::kStateApps, /*animate=*/false);
   // In side shelf, the opacity of the contents is not animated so set it to the
   // final state. In tablet mode, opacity of the elements is controlled by the
   // HomeLauncherGestureHandler which expects these elements to be opaque.