Flapper has some additional environment expectations.

content/ppapi_plugin/ppapi_plugin_main.cc

Index: content/ppapi_plugin/ppapi_plugin_main.cc
diff --git a/content/ppapi_plugin/ppapi_plugin_main.cc b/content/ppapi_plugin/ppapi_plugin_main.cc
index ed6897788717739452b8da4b550fad28bcaea45a..ec4d6b5fd9419a9674d302cf1e75bb74f855ce49 100644
--- a/content/ppapi_plugin/ppapi_plugin_main.cc
+++ b/content/ppapi_plugin/ppapi_plugin_main.cc
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include <stdlib.h>
+
 #include "base/command_line.h"
 #include "base/debug/debugger.h"
 #include "base/i18n/rtl.h"
@@ -53,6 +55,9 @@ int PpapiPluginMain(const content::MainFunctionParams& parameters) {
   if (command_line.HasSwitch(switches::kLang)) {
     std::string locale = command_line.GetSwitchValueASCII(switches::kLang);
     base::i18n::SetICUDefaultLocale(locale);
+    std::replace(locale.begin(), locale.end(), '-', '_');
+    setlocale(LC_ALL, locale.c_str());
+    setenv("LANG", locale.c_str(), 0);

[brettw, 2012/10/12 05:50:53]

Can you add a comment about why this is needed?

[Scott Hess - ex-Googler, 2012/10/12 06:15:05]

Done.  I'll poke around tomorrow morning and see if I can't make the comment
more specific or something (I only have chromium code access out here).

   }
 
   MessageLoop main_message_loop;