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

ui/app_list/app_list_constants.h

Index: ui/app_list/app_list_constants.h
diff --git a/ui/app_list/app_list_constants.h b/ui/app_list/app_list_constants.h
index f48671fd49a9d3b09fd8400c1b6f5fb6d8b99a63..7f5940e5463ffa6ac14de1bb159616261527b72e 100644
--- a/ui/app_list/app_list_constants.h
+++ b/ui/app_list/app_list_constants.h
@@ -34,11 +34,15 @@ 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 int kPreferredCols;
 APP_LIST_EXPORT extern const int kPreferredRows;
 APP_LIST_EXPORT extern const int kPreferredIconDimension;
 
+APP_LIST_EXPORT extern const size_t kNumFolderTopItems;
+
 APP_LIST_EXPORT extern const ui::ResourceBundle::FontStyle kItemTextFontStyle;
 
 }  // namespace app_list