[Mac]Implement ViewID support.

chrome/browser/cocoa/find_bar_text_field.mm

-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2010 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/cocoa/find_bar_text_field.h"
 
 #include "base/logging.h"
 #import "chrome/browser/cocoa/find_bar_text_field_cell.h"
+#import "chrome/browser/cocoa/view_id_util.h"
 
 @implementation FindBarTextField
 
 + (Class)cellClass {
   return [FindBarTextFieldCell class];
 }
 
 - (void)awakeFromNib {
   DCHECK([[self cell] isKindOfClass:[FindBarTextFieldCell class]]);
 }
 
 - (FindBarTextFieldCell*)findBarTextFieldCell {
   DCHECK([[self cell] isKindOfClass:[FindBarTextFieldCell class]]);
   return static_cast<FindBarTextFieldCell*>([self cell]);
 }
 
+// Tag is used solely for ViewID. Override to prevent changing of it.
+- (NSInteger)tag {
+  return view_id_util::ViewIDToTag(VIEW_ID_FIND_IN_PAGE_TEXT_FIELD);
+}
+
 @end