Run a nested message loop so that the browser doesn't hang.

chrome/renderer/pepper/ppb_pdf_impl.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.
 
 #include "chrome/renderer/pepper/ppb_pdf_impl.h"
 
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
 #include "base/safe_numerics.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 391 matching lines @@
                               PP_Var message) {
   content::PepperPluginInstance* instance =
       content::PepperPluginInstance::Get(instance_id);
   if (!instance)
     return PP_MakeUndefined();
 
   std::string actual_value;
   scoped_refptr<ppapi::StringVar> message_string(
       ppapi::StringVar::FromPPVar(message));
 
-  instance->GetRenderView()->Send(
-      new ChromeViewHostMsg_PDFModalPromptForPassword(
-          instance->GetRenderView()->GetRoutingID(),
-          message_string->value(),
-          &actual_value));
+  IPC::SyncMessage* msg = new ChromeViewHostMsg_PDFModalPromptForPassword(
+      instance->GetRenderView()->GetRoutingID(),
+      message_string->value(),
+      &actual_value);
+  msg->EnableMessagePumping();
+  instance->GetRenderView()->Send(msg);
 
   return ppapi::StringVar::StringToPPVar(actual_value);
 }
 
 const PPB_PDF ppb_pdf = {
   &GetLocalizedString,
   &GetResourceImage,
   &GetFontFileWithFallback,
   &GetFontTableForPrivateFontFile,
   &SearchString,
@@ skipping 19 matching lines @@
 
 // static
 void PPB_PDF_Impl::InvokePrintingForInstance(PP_Instance instance_id) {
 #if defined(ENABLE_FULL_PRINTING)
   WebKit::WebElement element = GetWebElement(instance_id);
   printing::PrintWebViewHelper* helper = GetPrintWebViewHelper(element);
   if (helper)
     helper->PrintNode(element);
 #endif  // ENABLE_FULL_PRINTING
 }