base: Add AsList() function to Value API.

chrome/test/automation/value_conversion_traits.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/test/automation/value_conversion_traits.h"
 
 #include "base/values.h"
 
 using base::DictionaryValue;
 using base::ListValue;
@@ skipping 53 matching lines @@
 bool ValueConversionTraits<Value*>::CanConvert(const Value* value) {
   return true;
 }
 
 Value* ValueConversionTraits<ListValue*>::CreateValueFrom(const ListValue* t) {
   return t->DeepCopy();
 }
 
 bool ValueConversionTraits<ListValue*>::SetFromValue(const Value* value,
                                                      ListValue** t) {
-  if (!value->IsType(Value::TYPE_LIST))
+  ListValue* list = const_cast<Value*>(value)->AsList();
+  if (!list)
     return false;
-  *t = static_cast<const ListValue*>(value)->DeepCopy();
+  *t = list->DeepCopy();
   return true;
 }
 
 bool ValueConversionTraits<ListValue*>::CanConvert(const Value* value) {
-  return value->IsType(Value::TYPE_LIST);
+  return const_cast<Value*>(value)->AsList();
 }
 
 Value* ValueConversionTraits<DictionaryValue*>::CreateValueFrom(
     const DictionaryValue* t) {
   return t->DeepCopy();
 }
 
 bool ValueConversionTraits<DictionaryValue*>::SetFromValue(
     const Value* value, DictionaryValue** t) {
   if (!value->IsType(Value::TYPE_DICTIONARY))
     return false;
   *t = static_cast<const DictionaryValue*>(value)->DeepCopy();
   return true;
 }
 
 bool ValueConversionTraits<DictionaryValue*>::CanConvert(const Value* value) {
   return value->IsType(Value::TYPE_DICTIONARY);
 }