[Extensions] Harden against bindings interception

extensions/renderer/module_system.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/module_system.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/macros.h"
@@ skipping 233 matching lines @@
   // background page keeps reference to chrome object in a closed popup).
   v8::Local<v8::Value> modules_value;
   if (!GetPrivate(global, kModulesField, &modules_value) ||
       modules_value->IsUndefined()) {
     Warn(GetIsolate(), "Extension view no longer exists");
     return v8::Undefined(GetIsolate());
   }
 
   v8::Local<v8::Object> modules(v8::Local<v8::Object>::Cast(modules_value));
   v8::Local<v8::Value> exports;
-  if (!GetProperty(v8_context, modules, module_name, &exports) ||
+  if (!GetPrivateProperty(v8_context, modules, module_name, &exports) ||
       !exports->IsUndefined())
     return handle_scope.Escape(exports);
 
   exports = LoadModule(*v8::String::Utf8Value(module_name));
-  SetProperty(v8_context, modules, module_name, exports);
+  SetPrivateProperty(v8_context, modules, module_name, exports);
   return handle_scope.Escape(exports);
 }
 
 v8::Local<v8::Value> ModuleSystem::CallModuleMethod(
     const std::string& module_name,
     const std::string& method_name) {
   v8::EscapableHandleScope handle_scope(GetIsolate());
   v8::Local<v8::Value> no_args;
   return handle_scope.Escape(
       CallModuleMethod(module_name, method_name, 0, &no_args));
@@ skipping 475 matching lines @@
 
 void ModuleSystem::ClobberExistingNativeHandler(const std::string& name) {
   NativeHandlerMap::iterator existing_handler = native_handler_map_.find(name);
   if (existing_handler != native_handler_map_.end()) {
     clobbered_native_handlers_.push_back(std::move(existing_handler->second));
     native_handler_map_.erase(existing_handler);
   }
 }
 
 }  // namespace extensions