Pacify Coverity when reading kExtensionsPref dictionary

chrome/browser/prefs/pref_service.cc

 // Copyright (c) 2011 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_service.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/command_line.h"
@@ skipping 391 matching lines @@
 
 const DictionaryValue* PrefService::GetDictionary(const char* path) const {
   DCHECK(CalledOnValidThread());
 
   const Preference* pref = FindPreference(path);
   if (!pref) {
     NOTREACHED() << "Trying to read an unregistered pref: " << path;
     return NULL;
   }
   const Value* value = pref->GetValue();
-  if (value->GetType() == Value::TYPE_NULL)
+  if (value->GetType() != Value::TYPE_DICTIONARY) {
+    NOTREACHED();
     return NULL;
+  }
   return static_cast<const DictionaryValue*>(value);
 }
 
 const ListValue* PrefService::GetList(const char* path) const {
   DCHECK(CalledOnValidThread());
 
   const Preference* pref = FindPreference(path);
   if (!pref) {
     NOTREACHED() << "Trying to read an unregistered pref: " << path;
     return NULL;
   }
   const Value* value = pref->GetValue();
-  if (value->GetType() == Value::TYPE_NULL)
+  if (value->GetType() != Value::TYPE_LIST) {
+    NOTREACHED();
     return NULL;
+  }
   return static_cast<const ListValue*>(value);
 }
 
 void PrefService::AddPrefObserver(const char* path,
                                   NotificationObserver* obs) {
   pref_notifier_->AddPrefObserver(path, obs);
 }
 
 void PrefService::RemovePrefObserver(const char* path,
                                      NotificationObserver* obs) {
@@ skipping 237 matching lines @@
 
 bool PrefService::Preference::IsDefaultValue() const {
   return pref_service_->pref_value_store_->
       PrefValueFromDefaultStore(name_.c_str());
 }
 
 bool PrefService::Preference::IsUserModifiable() const {
   return pref_service_->pref_value_store_->
       PrefValueUserModifiable(name_.c_str());
 }