Implement animation UI for opening/closing an app list folder.

ui/app_list/app_list_constants.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/app_list_constants.h"
 
 namespace app_list {
 
 const SkColor kContentsBackgroundColor = SkColorSetRGB(0xFB, 0xFB, 0xFB);
 const SkColor kSearchBoxBackground = SK_ColorWHITE;
@@ skipping 18 matching lines @@
 
 // Color of the folder ink bubble.
 const SkColor kFolderBubbleColor = SkColorSetRGB(0xD7, 0xD7, 0xD7);
 
 // Duration in milliseconds for page transition.
 const int kPageTransitionDurationInMs = 180;
 
 // Duration in milliseconds for over scroll page transition.
 const int kOverscrollPageTransitionDurationMs = 50;
 
+// Duration in milliseconds for the target page transition when opening or
+// closing a folder.
+const int kFolderTransitionInDurationMs = 200;
+
+// Duration in milliseconds for fading out the old page when opening or
+// closing a folder.
+const int kFolderTransitionOutDurationMs = 30;
+
 // Preferred number of columns and rows in apps grid.
 const int kPreferredCols = 4;
 const int kPreferredRows = 4;
 const int kPreferredIconDimension = 48;
 
+// Number of the top items in a folder, which are shown inside the folder icon
+// and animated when opening and closing a folder.
+const size_t kNumFolderTopItems = 4;
+
 // Font style for app item labels.
 const ui::ResourceBundle::FontStyle kItemTextFontStyle =
     ui::ResourceBundle::SmallBoldFont;
 
 }  // namespace app_list