Replace TOUCH_UI condition in WebUI with dynamic flag.

chrome/browser/resources/shared/js/cr/ui/card_slider.js

 // Copyright (c) 2011 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.
 
 /**
  * @fileoverview Card slider implementation. Allows you to create interactions
  * that have items that can slide left to right to reveal additional items.
  * Works by adding the necessary event handlers to a specific DOM structure
  * including a frame, container and cards.
  * - The frame defines the boundary of one item. Each card will be expanded to
@@ skipping 114 matching lines @@
 
       this.updateCardWidths_();
 
       this.mouseWheelScrollAmount_ = 0;
       this.mouseWheelCardSelected_ = false;
       this.mouseWheelIsContinuous_ = false;
       this.scrollClearTimeout_ = null;
       this.frame_.addEventListener('mousewheel',
                                    this.onMouseWheel_.bind(this));
 
-      if (document.documentElement.getAttribute('touchui')) {
-        var TouchHandler = cr.ui.TouchHandler;
-        this.container_.addEventListener(TouchHandler.EventType.TOUCH_START,
-                                         this.onTouchStart_.bind(this));
-        this.container_.addEventListener(TouchHandler.EventType.DRAG_START,
-                                         this.onDragStart_.bind(this));
-        this.container_.addEventListener(TouchHandler.EventType.DRAG_MOVE,
-                                         this.onDragMove_.bind(this));
-        this.container_.addEventListener(TouchHandler.EventType.DRAG_END,
-                                         this.onDragEnd_.bind(this));
+      // Also support touch events in case a touch screen happens to be
+      // available.  Note that we could check cr.isTouchOptimized here, but
+      // in general sites should just be listening for touch events without
+      // trying to determine in advance if they may be supported (eg. a touch
+      // screen can always be plugged in after a page has loaded).
+      var TouchHandler = cr.ui.TouchHandler;
+      this.container_.addEventListener(TouchHandler.EventType.TOUCH_START,
+                                       this.onTouchStart_.bind(this));
+      this.container_.addEventListener(TouchHandler.EventType.DRAG_START,
+                                       this.onDragStart_.bind(this));
+      this.container_.addEventListener(TouchHandler.EventType.DRAG_MOVE,
+                                       this.onDragMove_.bind(this));
+      this.container_.addEventListener(TouchHandler.EventType.DRAG_END,
+                                       this.onDragEnd_.bind(this));
 
-        this.touchHandler_.enable(/* opt_capture */ false);
-      }
+      this.touchHandler_.enable(/* opt_capture */ false);
     },
 
     /**
      * Use in cases where the width of the frame has changed in order to update
      * the width of cards. For example should be used when orientation changes
      * in full width sliders.
      * @param {number} newCardWidth Width all cards should have, in pixels.
      */
     resize: function(newCardWidth) {
       if (newCardWidth != this.cardWidth_) {
@@ skipping 293 matching lines @@
 
       // Ensure we're at a card bounary
       this.transformToCurrentCard_(true);
     },
   };
 
   return {
     CardSlider: CardSlider
   };
 });