[Mac]Implement ViewID support.

chrome/browser/cocoa/find_bar_text_field.mm

Index: chrome/browser/cocoa/find_bar_text_field.mm
diff --git a/chrome/browser/cocoa/find_bar_text_field.mm b/chrome/browser/cocoa/find_bar_text_field.mm
index 7873c02dcbf2e60ffcff5c864c3d2da96e0a81b4..2725afc54da3caf24aa7930e9ba8971be171bd85 100644
--- a/chrome/browser/cocoa/find_bar_text_field.mm
+++ b/chrome/browser/cocoa/find_bar_text_field.mm
@@ -1,4 +1,4 @@
-// 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.
 
@@ -6,6 +6,7 @@
 
 #include "base/logging.h"
 #import "chrome/browser/cocoa/find_bar_text_field_cell.h"
+#import "chrome/browser/cocoa/view_id_util.h"
 
 @implementation FindBarTextField
 
@@ -22,4 +23,9 @@
   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