[Chrome Settings UI] If User Exceptions are not allowed, prevent editing / viewing.

chrome/browser/resources/options/content_settings_exceptions_area.js

Index: chrome/browser/resources/options/content_settings_exceptions_area.js
diff --git a/chrome/browser/resources/options/content_settings_exceptions_area.js b/chrome/browser/resources/options/content_settings_exceptions_area.js
index 3ad7ac62a552f0e1079168e4d2c97cf12e4e61c1..4a27ecdfbcf0b018b1bca8f57a061bf6002412d4 100644
--- a/chrome/browser/resources/options/content_settings_exceptions_area.js
+++ b/chrome/browser/resources/options/content_settings_exceptions_area.js
@@ -520,6 +520,43 @@ cr.define('options.contentSettings', function() {
     },
 
     /**
+     * Updates visibility of each row, depending on content.
+     */
+    updateRowVisibility: function() {
+      // Rows with user exceptions are visible iff this.isEditable().
+      // All other rows are visible.
+      var isEditable = this.isEditable();
+      for (var index = 0; index < this.dataModel.length; ++index) {
+        var item = this.getListItemByIndex(index);
+        if (item.dataItem.source == 'preference')
+          item.hidden = !isEditable;
+      }
+    },
+
+    /**
+     * Sets whether user is allowed to set preference exceptions. Updates UI.
+     *
+     * @param {string} allowEdit Whether or not user may set preference
+     *    exceptions.
+     */
+    setAllowEdit: function(allowEdit) {
+      var oldIsEditable = this.isEditable();
+      this.allowEdit = allowEdit;
+      var newIsEditable = this.isEditable();
+
+      // If visibility changed, add or remove the Add New Exception row.
+      if (oldIsEditable != newIsEditable) {
+        var oldSize = this.dataModel.length;
+        if (newIsEditable) {
+          this.dataModel.push(null);
+        } else {
+          this.dataModel.splice(oldSize - 1, 1);  // pop.

[Evan Stade, 2016/04/26 16:05:16]

I would be in favor of adding pop to ArrayDataModel

[huangs, 2016/04/26 17:37:03]

ArrayDataModel stores raw list of data in |this.array_|, and the elements are
ordered by |this.indexes_|, sorting is applied to this order.  If we add pop()
then it will remove the "logical last element", i.e.,
this.array_[this.index_[this.index_.length - 1]]?

Meanwhile, it looks like ExceptionList is skipping all this sorting business
because |this.dataModel.sortStatus_.field| == null.  Rather than adding a more
general pop() that only we use, and without exercising its generality, I think
it's cleaner to just call splice() explicitly?

[Evan Stade, 2016/04/26 22:58:09]

Don't you think pop() would be useful in other places? It's likely that the only
reason it's not used anywhere else currently is because it doesn't exist and
everyone just keeps using splice.

[huangs, 2016/04/26 23:18:20]

My preference is to keep the CL small.  It seems adding pop() and refactoring
users for it should be an independent cleanup?  +dbeam@ for discussion.

[Dan Beam, 2016/04/27 02:29:39]

i don't really know much about ArrayDataModel, but could we just add pop() as an
alias for splice(this.length - 1, 1) basically with a TODO?

[huangs, 2016/04/27 14:28:01]

Added pop(). It returns the last item as well, for least surprise.

+        }
+      }
+      this.updateRowVisibility();
+    },
+
+    /**
      * Sets the exceptions in the js model.
      *
      * @param {Array<options.Exception>} entries A list of dictionaries of
@@ -536,6 +573,7 @@ cr.define('options.contentSettings', function() {
       var args = [0, deleteCount];
       args.push.apply(args, entries);
       this.dataModel.splice.apply(this.dataModel, args);
+      this.updateRowVisibility();
     },
 
     /**
@@ -562,14 +600,14 @@ cr.define('options.contentSettings', function() {
      * Returns whether the rows are editable in this list.
      */
     isEditable: function() {
-      // Exceptions of the following lists are not editable for now.
-      return isEditableType(this.contentType);
+      return this.allowEdit && isEditableType(this.contentType);
     },
 
     /**
      * Removes all exceptions from the js model.
      */
     reset: function() {
+      this.allowEdit = true;
       if (this.isEditable()) {
         // The null creates the Add New Exception row.
         this.dataModel = new ArrayDataModel([null]);