Use a background for the main search box in the experimental app list.

ui/app_list/app_list_constants.h

 // 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.
 
 #ifndef UI_APP_LIST_APP_LIST_CONSTANTS_H_
 #define UI_APP_LIST_APP_LIST_CONSTANTS_H_
 
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/app_list/app_list_export.h"
 #include "ui/base/resource/resource_bundle.h"
@@ skipping 17 matching lines @@
 APP_LIST_EXPORT extern const SkColor kPagerSelectedColor;
 
 APP_LIST_EXPORT extern const SkColor kResultBorderColor;
 APP_LIST_EXPORT extern const SkColor kResultDefaultTextColor;
 APP_LIST_EXPORT extern const SkColor kResultDimmedTextColor;
 APP_LIST_EXPORT extern const SkColor kResultURLTextColor;
 
 APP_LIST_EXPORT extern const SkColor kGridTitleColor;
 APP_LIST_EXPORT extern const SkColor kGridTitleHoverColor;
 
-APP_LIST_EXPORT extern const SkColor kStartPageBorderColor;
-
 APP_LIST_EXPORT extern const SkColor kFolderBubbleColor;
 
 APP_LIST_EXPORT extern const int kPageTransitionDurationInMs;
 APP_LIST_EXPORT extern const int kOverscrollPageTransitionDurationMs;
 APP_LIST_EXPORT extern const int kFolderTransitionInDurationMs;
 APP_LIST_EXPORT extern const int kFolderTransitionOutDurationMs;
 APP_LIST_EXPORT extern const gfx::Tween::Type kFolderFadeInTweenType;
 APP_LIST_EXPORT extern const gfx::Tween::Type kFolderFadeOutTweenType;
 
 APP_LIST_EXPORT extern const int kPreferredCols;
@@ skipping 17 matching lines @@
 APP_LIST_EXPORT extern const ui::ResourceBundle::FontStyle kItemTextFontStyle;
 
 #if defined(OS_LINUX)
 // The WM_CLASS name for the app launcher window on Linux.
 APP_LIST_EXPORT extern const char kAppListWMClass[];
 #endif
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_APP_LIST_CONSTANTS_H_