Reland "Update and clarify view ownership for app-list views."

This is a reland of fe842ad4

Original change's description:
> Update and clarify view ownership for app-list views.
> 
> Bug: 648382
> Change-Id: I0d000accee686dd67b2db1e14cea20ff893835c5
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2001399
> Commit-Queue: Allen Bauer <kylixrd@chromium.org>
> Reviewed-by: Alex Newcomer <newcomer@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#732019}

Bug: 648382
Change-Id: I07aa57e7b497367fd5699bf997dc76c6f36f355c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2012835Reviewed-by: Alex Newcomer <newcomer@chromium.org>
Commit-Queue: Allen Bauer <kylixrd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#734244}

ash/app_list/views/app_list_main_view.cc

@@ -49,8 +49,6 @@ AppListMainView::AppListMainView(AppListViewDelegate* delegate,
     : delegate_(delegate),
       model_(delegate->GetModel()),
       search_model_(delegate->GetSearchModel()),
-      search_box_view_(nullptr),
-      contents_view_(nullptr),
       app_list_view_(app_list_view) {
   // We need a layer to apply transform to in small display so that the apps
   // grid fits in the display.
@@ -77,11 +75,11 @@ void AppListMainView::Init(int initial_apps_page,
 
 void AppListMainView::AddContentsViews() {
   DCHECK(search_box_view_);
-  contents_view_ = new ContentsView(app_list_view_);
-  contents_view_->Init(model_);
-  contents_view_->SetPaintToLayer(ui::LAYER_NOT_DRAWN);
-  contents_view_->layer()->SetMasksToBounds(true);
-  AddChildView(contents_view_);
+  auto contents_view = std::make_unique<ContentsView>(app_list_view_);
+  contents_view->Init(model_);
+  contents_view->SetPaintToLayer(ui::LAYER_NOT_DRAWN);
+  contents_view->layer()->SetMasksToBounds(true);
+  contents_view_ = AddChildView(std::move(contents_view));
 
   search_box_view_->set_contents_view(contents_view_);
 }

ash/app_list/views/app_list_main_view.h

@@ -99,10 +99,10 @@ class APP_LIST_EXPORT AppListMainView
   SearchModel* search_model_;  // Unowned; ownership is handled by |delegate_|.
 
   // Created by AppListView. Owned by views hierarchy.
-  SearchBoxView* search_box_view_;
+  SearchBoxView* search_box_view_ = nullptr;
 
-  ContentsView* contents_view_;       // Owned by views hierarchy.
-  AppListView* const app_list_view_;  // Owned by views hierarchy.
+  ContentsView* contents_view_ = nullptr;  // Owned by views hierarchy.
+  AppListView* const app_list_view_;       // Owned by views hierarchy.
 
   DISALLOW_COPY_AND_ASSIGN(AppListMainView);
 };

ash/app_list/views/app_list_view.cc

@@ -618,20 +618,24 @@ void AppListView::InitContents(bool is_tablet_mode) {
   DCHECK(!search_box_view_);
   DCHECK(!announcement_view_);
 
+  auto app_list_background_shield =
+      std::make_unique<AppListBackgroundShieldView>(delegate_->GetShelfSize() /
+                                                    2);
+  app_list_background_shield->UpdateBackground(/*use_blur*/ !is_tablet_mode &&
+                                               is_background_blur_enabled_);
   app_list_background_shield_ =
-      new AppListBackgroundShieldView(delegate_->GetShelfSize() / 2);
-  app_list_background_shield_->UpdateBackground(/*use_blur*/ !is_tablet_mode &&
-                                                is_background_blur_enabled_);
-  AddChildView(app_list_background_shield_);
+      AddChildView(std::move(app_list_background_shield));
 
-  app_list_main_view_ = new AppListMainView(delegate_, this);
-  search_box_view_ = new SearchBoxView(app_list_main_view_, delegate_, this);
+  auto app_list_main_view = std::make_unique<AppListMainView>(delegate_, this);
+  search_box_view_ =
+      new SearchBoxView(app_list_main_view.get(), delegate_, this);
   search_box_view_->Init(is_tablet_mode);
 
-  app_list_main_view_->Init(0, search_box_view_);
-  AddChildView(app_list_main_view_);
-  announcement_view_ = new views::View();
-  AddChildView(announcement_view_);
+  // Assign |app_list_main_view_| here since it is accessed during Init().
+  app_list_main_view_ = app_list_main_view.get();
+  app_list_main_view->Init(0, search_box_view_);
+  AddChildView(std::move(app_list_main_view));
+  announcement_view_ = AddChildView(std::make_unique<views::View>());
 }
 
 void AppListView::InitWidget(gfx::NativeView parent) {

ash/app_list/views/apps_container_view.cc

@@ -62,25 +62,26 @@ AppsContainerView::AppsContainerView(ContentsView* contents_view,
     : contents_view_(contents_view) {
   SetPaintToLayer(ui::LAYER_NOT_DRAWN);
 
-  suggestion_chip_container_view_ =
-      new SuggestionChipContainerView(contents_view);
-  AddChildView(suggestion_chip_container_view_);
+  suggestion_chip_container_view_ = AddChildView(
+      std::make_unique<SuggestionChipContainerView>(contents_view));
 
-  apps_grid_view_ = new AppsGridView(contents_view_, nullptr);
-  AddChildView(apps_grid_view_);
+  apps_grid_view_ =
+      AddChildView(std::make_unique<AppsGridView>(contents_view_, nullptr));
 
   // Page switcher should be initialized after AppsGridView.
-  page_switcher_ =
-      new PageSwitcher(apps_grid_view_->pagination_model(), true /* vertical */,
-                       contents_view_->app_list_view()->is_tablet_mode());
-  AddChildView(page_switcher_);
+  auto page_switcher = std::make_unique<PageSwitcher>(
+      apps_grid_view_->pagination_model(), true /* vertical */,
+      contents_view_->app_list_view()->is_tablet_mode());
+  page_switcher_ = AddChildView(std::move(page_switcher));
 
-  app_list_folder_view_ = new AppListFolderView(this, model, contents_view_);
+  auto app_list_folder_view =
+      std::make_unique<AppListFolderView>(this, model, contents_view_);
   // The folder view is initially hidden.
-  app_list_folder_view_->SetVisible(false);
-  folder_background_view_ = new FolderBackgroundView(app_list_folder_view_);
-  AddChildView(folder_background_view_);
-  AddChildView(app_list_folder_view_);
+  app_list_folder_view->SetVisible(false);
+  auto folder_background_view =
+      std::make_unique<FolderBackgroundView>(app_list_folder_view.get());
+  folder_background_view_ = AddChildView(std::move(folder_background_view));
+  app_list_folder_view_ = AddChildView(std::move(app_list_folder_view));
 
   apps_grid_view_->SetModel(model);
   apps_grid_view_->SetItemList(model->top_level_item_list());

ash/app_list/views/apps_grid_view.h

@@ -347,7 +347,7 @@ class APP_LIST_EXPORT AppsGridView : public views::View,
   // number of apps.
   void UpdatePulsingBlockViews();
 
-  AppListItemView* CreateViewForItemAtIndex(size_t index);
+  std::unique_ptr<AppListItemView> CreateViewForItemAtIndex(size_t index);
 
   // Returns true if the event was handled by the pagination controller.
   bool HandleScroll(const gfx::Vector2d& offset, ui::EventType type);