[Mac] Support undo in the omnibox.

chrome/browser/cocoa/autocomplete_text_field_unittest.mm

 // Copyright (c) 2009 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 <Cocoa/Cocoa.h>
 
 #import "base/cocoa_protocols_mac.h"
 #include "base/scoped_nsobject.h"
 #import "chrome/browser/cocoa/autocomplete_text_field.h"
 #import "chrome/browser/cocoa/autocomplete_text_field_cell.h"
@@ skipping 653 matching lines @@
   EXPECT_FALSE([undoManager canUndo]);
 
   // Verify that -setAttributedStringValue: does not reset the
   // editor's undo chain.
   [field_ setStringValue:@""];
   [editor shouldChangeTextInRange:NSMakeRange(0, 0) replacementString:@""];
   [editor didChangeText];
   EXPECT_TRUE([undoManager canUndo]);
   [field_ setAttributedStringValue:attributedString];
   EXPECT_TRUE([undoManager canUndo]);
+
+  // Verify that calling -clearUndoChain clears the undo chain.
+  [field_ clearUndoChain];
+  EXPECT_FALSE([undoManager canUndo]);
 }
 
+TEST_F(AutocompleteTextFieldTest, EditorGetsCorrectUndoManager) {
+  cocoa_helper_.makeFirstResponder(field_);
+
+  NSTextView* editor = static_cast<NSTextView*>([field_ currentEditor]);
+  EXPECT_TRUE(editor);
+  EXPECT_EQ([field_ undoManagerForTextView:editor], [editor undoManager]);
+}
 }  // namespace