Modify chooser controller to correctly handle removing item on Mac

chrome/browser/ui/cocoa/extensions/chooser_dialog_cocoa_controller.mm

 // Copyright 2016 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.
 
 #import "chrome/browser/ui/cocoa/extensions/chooser_dialog_cocoa_controller.h"
 
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #import "chrome/browser/ui/cocoa/chooser_content_view.h"
 #import "chrome/browser/ui/cocoa/extensions/chooser_dialog_cocoa.h"
@@ skipping 91 matching lines @@
 
 - (void)onOptionsInitialized {
   [self updateTableView];
 }
 
 - (void)onOptionAdded:(NSInteger)index {
   [self updateTableView];
 }
 
 - (void)onOptionRemoved:(NSInteger)index {
-  // |tableView_| will automatically selects the next item if the current
-  // item is removed, so here it tracks if the removed item is the item
-  // that was previously selected, if so, deselect it.
-  if ([tableView_ selectedRow] == index)
+  // |tableView_| will automatically select the removed item's next item.
+  // So here it tracks if the removed item is the item that was currently
+  // selected, if so, deselect it. Also if the removed item is before the
+  // currently selected item, the currently selected item's index needs to
+  // be adjusted by one.
+  NSInteger selectedRow = [tableView_ selectedRow];
+  if (selectedRow == index)
     [tableView_ deselectRow:index];
+  else if (selectedRow > index)
+    [tableView_ selectRowIndexes:[NSIndexSet indexSetWithIndex:selectedRow - 1]
+            byExtendingSelection:NO];
 
   [self updateTableView];
 }
 
 - (void)updateTableView {
   [tableView_ setEnabled:chooserController_->NumOptions() > 0];
   [tableView_ reloadData];
 }
 
 - (void)tableViewSelectionDidChange:(NSNotification*)aNotification {
@@ skipping 13 matching lines @@
 
 - (void)onHelpPressed:(id)sender {
   chooserController_->OpenHelpCenterUrl();
 }
 
 - (ChooserContentView*)chooserContentView {
   return chooserContentView_.get();
 }
 
 @end