app_list: Fix possible out of bounds index.

ui/app_list/test/app_list_test_model.cc

Index: ui/app_list/test/app_list_test_model.cc
diff --git a/ui/app_list/test/app_list_test_model.cc b/ui/app_list/test/app_list_test_model.cc
index 70b60a882f930ac8aec194fe6ed1af6a042912e7..9a81aab40014917b9183e358394a082b830319df 100644
--- a/ui/app_list/test/app_list_test_model.cc
+++ b/ui/app_list/test/app_list_test_model.cc
@@ -7,11 +7,22 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/stringprintf.h"
 #include "grit/ui_resources.h"
+#include "third_party/skia/include/core/SkBitmap.h"
+#include "ui/app_list/app_list_constants.h"
 #include "ui/base/resource/resource_bundle.h"
+#include "ui/gfx/image/image_skia.h"
 
 namespace app_list {
 namespace test {
 
+gfx::ImageSkia CreateImageSkia(int width, int height) {
+  SkBitmap bitmap;
+  bitmap.setConfig(SkBitmap::kARGB_8888_Config, width, height);
+  bitmap.allocPixels();
+  bitmap.eraseARGB(255, 0, 255, 0);
+  return gfx::ImageSkia::CreateFrom1xBitmap(bitmap);
+}
+
 // static
 const char AppListTestModel::kItemType[] = "TestItem";
 
@@ -22,6 +33,8 @@ AppListTestModel::AppListTestItem::AppListTestItem(
     AppListTestModel* model)
     : AppListItem(id),
       model_(model) {
+  SetIcon(CreateImageSkia(kPreferredIconDimension, kPreferredIconDimension),
+          false /* has_shadow */);
 }
 
 AppListTestModel::AppListTestItem::~AppListTestItem() {
@@ -93,6 +106,16 @@ AppListFolderItem* AppListTestModel::CreateAndAddOemFolder(
   return static_cast<AppListFolderItem*>(AddItem(folder));
 }
 
+AppListFolderItem* AppListTestModel::CreateSingleItemFolder(
+    const std::string& folder_id,
+    const std::string& item_id) {
+  AppListTestItem* item = CreateItem(item_id);
+  AddItemToFolder(item, folder_id);
+  AppListItem* folder_item = FindItem(folder_id);
+  DCHECK(folder_item->GetItemType() == AppListFolderItem::kItemType);
+  return static_cast<AppListFolderItem*>(folder_item);
+}
+
 void AppListTestModel::PopulateAppWithId(int id) {
   CreateAndAddItem(GetItemName(id));
 }