Avoid using NULL comparison to check if element is in the map.

ppapi/native_client/src/trusted/plugin/plugin.cc

 // 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.
 
 #ifdef _MSC_VER
 // Do not warn about use of std::copy with raw pointers.
 #pragma warning(disable : 4996)
 #endif
 
 #include "native_client/src/trusted/plugin/plugin.h"
@@ skipping 423 matching lines @@
 void Plugin::AddPropertyGet(const nacl::string& prop_name,
                             Plugin::PropertyGetter getter) {
   PLUGIN_PRINTF(("Plugin::AddPropertyGet (prop_name='%s')\n",
                  prop_name.c_str()));
   property_getters_[nacl::string(prop_name)] = getter;
 }
 
 bool Plugin::HasProperty(const nacl::string& prop_name) {
   PLUGIN_PRINTF(("Plugin::HasProperty (prop_name=%s)\n",
                  prop_name.c_str()));
-  return property_getters_[prop_name] != NULL;
+  return property_getters_.find(prop_name) != property_getters_.end();
 }
 
 bool Plugin::GetProperty(const nacl::string& prop_name,
                          NaClSrpcArg* prop_value) {
   PLUGIN_PRINTF(("Plugin::GetProperty (prop_name=%s)\n", prop_name.c_str()));
 
-  PropertyGetter getter = property_getters_[prop_name];
-  if (NULL == getter) {
+  if (property_getters_.find(prop_name) == property_getters_.end()) {
     return false;
   }
+  PropertyGetter getter = property_getters_[prop_name];
   (this->*getter)(prop_value);
   return true;
 }
 
 void Plugin::GetExitStatus(NaClSrpcArg* prop_value) {
   PLUGIN_PRINTF(("GetExitStatus (this=%p)\n", reinterpret_cast<void*>(this)));
   prop_value->tag = NACL_SRPC_ARG_TYPE_INT;
   prop_value->u.ival = exit_status();
 }
 
@@ skipping 1420 matching lines @@
                                           static_cast<uint32_t>(text.size()));
   const PPB_Console_Dev* console_interface =
       static_cast<const PPB_Console_Dev*>(
           module->GetBrowserInterface(PPB_CONSOLE_DEV_INTERFACE));
   console_interface->LogWithSource(pp_instance(), PP_LOGLEVEL_LOG, prefix, str);
   var_interface->Release(prefix);
   var_interface->Release(str);
 }
 
 }  // namespace plugin