Fix the Crash in the launcher's start page (a better approach).

ui/app_list/views/start_page_view.cc

Index: ui/app_list/views/start_page_view.cc
diff --git a/ui/app_list/views/start_page_view.cc b/ui/app_list/views/start_page_view.cc
index 0bac15b7b2ab6f8edd0963a7683af447347acb52..fd5b60748d9719fc5997525c41b6f02fe93f6917 100644
--- a/ui/app_list/views/start_page_view.cc
+++ b/ui/app_list/views/start_page_view.cc
@@ -126,8 +126,6 @@ class StartPageView::StartPageTilesContainer
   AllAppsTileItemView* all_apps_button() { return all_apps_button_; }
 
   // Overridden from SearchResultContainerView:
-  int Update() override;
-  void UpdateSelectedIndex(int old_selected, int new_selected) override;
   void OnContainerSelected(bool from_bottom,
                            bool directional_movement) override;
   void NotifyFirstResultYIndex(int y_index) override;
@@ -136,6 +134,10 @@ class StartPageView::StartPageTilesContainer
  private:
   void CreateAppsGrid(int apps_num);
 
+  // Overridden from SearchResultContainerView:
+  int DoUpdate() override;
+  void UpdateSelectedIndex(int old_selected, int new_selected) override;

[xiyuan, 2017/01/04 00:12:09]

nit: I don't have a strong preference of whether to keep overridden method
private. But we should probably keep them together. That is, either move the
remaining ones here or put those two back.

[xdai1, 2017/01/04 00:30:20]

Just curious, why should we keep the overridden methods together?

[xiyuan, 2017/01/04 00:36:27]

Think that would make it easier to read. And style guide says to keep similar
declarations together.

https://google.github.io/styleguide/cppguide.html#Declaration_Order

[xdai1, 2017/01/04 23:18:41]

Done. Thanks for the reference!

+
   ContentsView* contents_view_;
   AppListViewDelegate* view_delegate_;
 
@@ -171,53 +173,6 @@ TileItemView* StartPageView::StartPageTilesContainer::GetTileItemView(
   return search_result_tile_views_[index];
 }
 
-int StartPageView::StartPageTilesContainer::Update() {
-  // Ignore updates and disable buttons when transitioning to a different
-  // state.
-  if (contents_view_->GetActiveState() != AppListModel::STATE_START) {
-    for (auto* view : search_result_tile_views_)
-      view->SetEnabled(false);
-
-    return num_results();
-  }
-
-  std::vector<SearchResult*> display_results =
-      AppListModel::FilterSearchResultsByDisplayType(
-          results(), SearchResult::DISPLAY_RECOMMENDATION, kNumStartPageTiles);
-  if (display_results.size() != search_result_tile_views_.size()) {
-    // We should recreate the grid layout in this case.
-    for (size_t i = 0; i < search_result_tile_views_.size(); ++i)
-      delete search_result_tile_views_[i];
-    search_result_tile_views_.clear();
-    RemoveChildView(all_apps_button_);
-    CreateAppsGrid(std::min(kNumStartPageTiles, display_results.size()));
-  }
-
-  // Update the tile item results.
-  for (size_t i = 0; i < search_result_tile_views_.size(); ++i) {
-    SearchResult* item = nullptr;
-    if (i < display_results.size())
-      item = display_results[i];
-    search_result_tile_views_[i]->SetSearchResult(item);
-    search_result_tile_views_[i]->SetEnabled(true);
-  }
-
-  Layout();
-  parent()->Layout();
-  // Add 1 to the results size to account for the all apps button.
-  return display_results.size() + 1;
-}
-
-void StartPageView::StartPageTilesContainer::UpdateSelectedIndex(
-    int old_selected,
-    int new_selected) {
-  if (old_selected >= 0)
-    GetTileItemView(old_selected)->SetSelected(false);
-
-  if (new_selected >= 0)
-    GetTileItemView(new_selected)->SetSelected(true);
-}
-
 void StartPageView::StartPageTilesContainer::OnContainerSelected(
     bool /*from_bottom*/,
     bool /*directional_movement*/) {
@@ -269,6 +224,53 @@ void StartPageView::StartPageTilesContainer::CreateAppsGrid(int apps_num) {
   AddChildView(all_apps_button_);
 }
 
+int StartPageView::StartPageTilesContainer::DoUpdate() {
+  // Ignore updates and disable buttons when transitioning to a different
+  // state.
+  if (contents_view_->GetActiveState() != AppListModel::STATE_START) {
+    for (auto* view : search_result_tile_views_)
+      view->SetEnabled(false);
+
+    return num_results();
+  }
+
+  std::vector<SearchResult*> display_results =
+      AppListModel::FilterSearchResultsByDisplayType(
+          results(), SearchResult::DISPLAY_RECOMMENDATION, kNumStartPageTiles);
+  if (display_results.size() != search_result_tile_views_.size()) {
+    // We should recreate the grid layout in this case.
+    for (size_t i = 0; i < search_result_tile_views_.size(); ++i)
+      delete search_result_tile_views_[i];
+    search_result_tile_views_.clear();
+    RemoveChildView(all_apps_button_);
+    CreateAppsGrid(std::min(kNumStartPageTiles, display_results.size()));
+  }
+
+  // Update the tile item results.
+  for (size_t i = 0; i < search_result_tile_views_.size(); ++i) {
+    SearchResult* item = nullptr;
+    if (i < display_results.size())
+      item = display_results[i];
+    search_result_tile_views_[i]->SetSearchResult(item);
+    search_result_tile_views_[i]->SetEnabled(true);
+  }
+
+  Layout();
+  parent()->Layout();
+  // Add 1 to the results size to account for the all apps button.
+  return display_results.size() + 1;
+}
+
+void StartPageView::StartPageTilesContainer::UpdateSelectedIndex(
+    int old_selected,
+    int new_selected) {
+  if (old_selected >= 0 && old_selected < num_results())
+    GetTileItemView(old_selected)->SetSelected(false);
+
+  if (new_selected >= 0 && new_selected < num_results())
+    GetTileItemView(new_selected)->SetSelected(true);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // StartPageView implementation:
 StartPageView::StartPageView(AppListMainView* app_list_main_view,
@@ -360,8 +362,8 @@ void StartPageView::OnShown() {
     custom_page_view->SetVisible(
         app_list_main_view_->ShouldShowCustomLauncherPage());
   }
-  tiles_container_->Update();
   tiles_container_->ClearSelectedIndex();
+  tiles_container_->Update();
   custom_launcher_page_background_->SetSelected(false);
 }