TableView: 3-phase ToggleSortOrder (sorted/reversed/unsorted)

ui/views/controls/table/table_view.h

Index: ui/views/controls/table/table_view.h
diff --git a/ui/views/controls/table/table_view.h b/ui/views/controls/table/table_view.h
index fc7f028164b02290c2163a4e74dc88f2acd65c6a..13ff7052f21bb13d0b11c80b12d39e5a9be20304 100644
--- a/ui/views/controls/table/table_view.h
+++ b/ui/views/controls/table/table_view.h
@@ -154,10 +154,17 @@ class VIEWS_EXPORT TableView
   // Sets the width of the column. |index| is in terms of |visible_columns_|.
   void SetVisibleColumnWidth(int index, int width);
 
-  // Toggles the sort order of the specified visible column index.
+  // Modify the table sort order, depending on a clicked column and the previous
+  // table sort order. Does nothing if this column is not sortable.
+  //
+  // When called repeatedly on the same sortable column, the sort order will
+  // cycle through three states in order: sorted -> reverse-sorted -> unsorted.
+  // When switching from one sort column to another, the previous sort column
+  // will be remembered and used as a secondary sort key.
   void ToggleSortOrder(int visible_column_index);
 
   const SortDescriptors& sort_descriptors() const { return sort_descriptors_; }
+  void SetSortDescriptors(SortDescriptors descriptors);

[sky, 2016/07/18 16:18:58]

nit: const SortDescriptors& . I realize what you have is likely just as
efficient, but seeing the value type requires more thought than had you just
used a const&.

[ncarter (slow), 2016/07/25 20:04:01]

Done.

   bool is_sorted() const { return !sort_descriptors_.empty(); }
 
   // Maps from the index in terms of the model to that of the view.
@@ -227,9 +234,6 @@ class VIEWS_EXPORT TableView
   // Invoked when the number of rows changes in some way.
   void NumRowsChanged();
 
-  // Resets the sort descriptions.
-  void SetSortDescriptors(const SortDescriptors& sort_descriptors);

[sky, 2016/07/18 16:18:58]

Move implementation to match new location.

[ncarter (slow), 2016/07/25 20:04:01]

Done.

-
   // Does the actual sort and updates the mappings (|view_to_model_| and
   // |model_to_view_|) appropriately.
   void SortItemsAndUpdateMapping();