app_list: Fix crash after uninstalling last app.

ui/app_list/apps_grid_view_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/app_list/apps_grid_view.h"
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
@@ skipping 50 matching lines @@
     AppListItemModel* item = new AppListItemModel;
     item->SetTitle(title);
     return item;
   }
 
   void HighlightItemAt(int index) {
     AppListItemModel* item = apps_model_->GetItemAt(index);
     item->SetHighlighted(true);
   }
 
+  AppListItemView* GetItemViewAt(int index) {
+    DCHECK(index >= 0 && index < apps_grid_view_->child_count());
+    return static_cast<AppListItemView*>(apps_grid_view_->child_at(index));
+  }
+
   scoped_ptr<AppListModel::Apps> apps_model_;
   scoped_ptr<PaginationModel> pagination_model_;
   scoped_ptr<AppsGridView> apps_grid_view_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(AppsGridViewTest);
 };
 
 TEST_F(AppsGridViewTest, CreatePage) {
   // Fully populates a page.
@@ skipping 21 matching lines @@
 
   // Highlight first one on 2nd page and 2nd page should be selected.
   HighlightItemAt(apps_grid_view_->tiles_per_page() + 1);
   EXPECT_EQ(1, pagination_model_->selected_page());
 
   // Highlight last one in the model and last page should be selected.
   HighlightItemAt(apps_model_->item_count() - 1);
   EXPECT_EQ(kPages - 1, pagination_model_->selected_page());
 }
 
+TEST_F(AppsGridViewTest, RemoveSelectedLastApp) {
+  const int kTotalItems = 2;
+  const int kLastItemIndex = kTotalItems - 1;
+
+  PopulateApps(kTotalItems);
+
+  AppListItemView* last_item = GetItemViewAt(kLastItemIndex);
+  apps_grid_view_->SetSelectedItem(last_item);
+  apps_model_->DeleteAt(kLastItemIndex);
+
+  EXPECT_FALSE(apps_grid_view_->IsSelectedItem(last_item));
+
+  // No crash happens.
+  AppListItemView* item = GetItemViewAt(0);
+  apps_grid_view_->SetSelectedItem(item);
+  EXPECT_TRUE(apps_grid_view_->IsSelectedItem(item));
+}
+
 }  // namespace test
 }  // namespace app_list