Avoid the possibility of future conflict with another address-of-static due to COMDAT folding.

components/user_prefs/user_prefs.cc

 // Copyright 2013 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.
 
 #include "components/user_prefs/user_prefs.h"
 
 #include "base/logging.h"
 #include "base/memory/singleton.h"
 #include "base/prefs/pref_service.h"
 #include "content/public/browser/browser_context.h"
 
 namespace components {
 
 namespace {
 
 void* UserDataKey() {
-  // We just need a unique constant. Use the address of this static member.
-  return reinterpret_cast<void*>(&UserPrefs::Get);
+  // We just need a unique constant. Use the address of a static that
+  // COMDAT folding won't touch in an optimizing linker.
+  static int data_key = 0;
+  return reinterpret_cast<void*>(&data_key);
 }
 
 }  // namespace
 
 // static
 PrefService* UserPrefs::Get(content::BrowserContext* context) {
   DCHECK(context);
   return static_cast<UserPrefs*>(
       context->GetUserData(UserDataKey()))->prefs_;
 }
 
 // static
 void UserPrefs::Set(content::BrowserContext* context, PrefService* prefs) {
   DCHECK(context);
   DCHECK(prefs);
   DCHECK(!context->GetUserData(UserDataKey()));
   context->SetUserData(UserDataKey(), new UserPrefs(prefs));
 }
 
 UserPrefs::UserPrefs(PrefService* prefs) : prefs_(prefs) {
 }
 
 UserPrefs::~UserPrefs() {
 }
 
 }  // namespace components