GuestView constants are now frozen (and thus actually constant).

extensions/renderer/safe_builtins.cc

 // Copyright 2014 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 "extensions/renderer/safe_builtins.h"
 
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "base/strings/stringprintf.h"
 #include "extensions/renderer/script_context.h"
@@ skipping 48 matching lines @@
     "  safe.self = builtin;\n"
     "  makeCallable(builtin.prototype, safe, false, protoPropertyNames);\n"
     "  if (staticPropertyNames)\n"
     "    makeCallable(builtin, safe, true, staticPropertyNames);\n"
     "  Save(builtin.name, safe);\n"
     "}\n"
     "\n"
     "// Save only what is needed by the extension modules.\n"
     "saveBuiltin(Object,\n"
     "            ['hasOwnProperty'],\n"
-    "            ['create', 'defineProperty', 'getOwnPropertyDescriptor',\n"
-    "             'getPrototypeOf', 'keys']);\n"
+    "            ['create', 'defineProperty', 'freeze',\n"
+    "             'getOwnPropertyDescriptor', 'getPrototypeOf', 'keys']);\n"
     "saveBuiltin(Function,\n"
     "            ['apply', 'bind', 'call']);\n"
     "saveBuiltin(Array,\n"
     "            ['concat', 'forEach', 'indexOf', 'join', 'push', 'slice',\n"
     "             'splice', 'map', 'filter']);\n"
     "saveBuiltin(String,\n"
     "            ['indexOf', 'slice', 'split']);\n"
     "saveBuiltin(RegExp,\n"
     "            ['test']);\n"
     "saveBuiltin(Error,\n"
@@ skipping 151 matching lines @@
 
 v8::Local<v8::Object> SafeBuiltins::GetString() const {
   return Load("String", context_->v8_context());
 }
 
 v8::Local<v8::Object> SafeBuiltins::GetError() const {
   return Load("Error", context_->v8_context());
 }
 
 }  //  namespace extensions