Relanding this as this did not fix the chromiumos breakage.

chrome/browser/prefs/pref_member.cc

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 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 "chrome/browser/prefs/pref_member.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/value_conversions.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/common/chrome_notification_types.h"
@@ skipping 16 matching lines @@
 void PrefMemberBase::Init(const char* pref_name,
                           PrefService* prefs,
                           content::NotificationObserver* observer) {
   DCHECK(pref_name);
   DCHECK(prefs);
   DCHECK(pref_name_.empty());  // Check that Init is only called once.
   observer_ = observer;
   prefs_ = prefs;
   pref_name_ = pref_name;
   // Check that the preference is registered.
-  DCHECK(prefs_->FindPreference(pref_name_.c_str()));
+  DCHECK(prefs_->FindPreference(pref_name_.c_str()))
+      << pref_name << " not registered.";
 
   // Add ourselves as a pref observer so we can keep our local value in sync.
   prefs_->AddPrefObserver(pref_name, this);
 }
 
 void PrefMemberBase::Destroy() {
   if (prefs_ && !pref_name_.empty()) {
     prefs_->RemovePrefObserver(pref_name_.c_str(), this);
     prefs_ = NULL;
   }
@@ skipping 113 matching lines @@
 template <>
 void PrefMember<FilePath>::UpdatePref(const FilePath& value) {
   prefs()->SetFilePath(pref_name().c_str(), value);
 }
 
 template <>
 bool PrefMember<FilePath>::Internal::UpdateValueInternal(const Value& value)
     const {
   return base::GetValueAsFilePath(value, &value_);
 }