app_list: Fix possible out of bounds index.

ui/app_list/cocoa/apps_grid_controller_unittest.mm

 // Copyright 2013 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 "base/mac/foundation_util.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/strings/utf_string_conversions.h"
 #include "skia/ext/skia_utils_mac.h"
 #import "testing/gtest_mac.h"
 #include "ui/app_list/app_list_constants.h"
@@ skipping 436 matching lines @@
   EXPECT_NSEQ(@"Item 2", [button title]);
   EXPECT_EQ(std::string("|Item 0,Item 1,Item 2|"), GetViewContent());
 
   // Update the title via the ItemModelObserver.
   app_list::AppListItem* item_model =
       model()->top_level_item_list()->item_at(2);
   model()->SetItemName(item_model, "UpdatedItem");
   EXPECT_NSEQ(@"UpdatedItem", [button title]);
 
   // Test icon updates through the model observer by ensuring the icon changes.
+  item_model->SetIcon(gfx::ImageSkia(), false);
   NSSize icon_size = [[button image] size];
   EXPECT_EQ(0, icon_size.width);
   EXPECT_EQ(0, icon_size.height);
 
   SkBitmap bitmap;
   const int kTestImageSize = 10;
   const int kTargetImageSize = 48;
   bitmap.setConfig(SkBitmap::kARGB_8888_Config, kTestImageSize, kTestImageSize);
   item_model->SetIcon(gfx::ImageSkia::CreateFrom1xBitmap(bitmap), false);
   icon_size = [[button image] size];
@@ skipping 521 matching lines @@
   // Test that a button being held down with the left button does not also show
   // a context menu.
   [GetItemViewAt(0) highlight:YES];
   EXPECT_FALSE([page menuForEvent:mouse_at_cell_0]);
   [GetItemViewAt(0) highlight:NO];
   EXPECT_TRUE([page menuForEvent:mouse_at_cell_0]);
 }
 
 }  // namespace test
 }  // namespace app_list