Send replies to sync IPCs from swapped out renderers.

content/common/swapped_out_messages.cc

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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 "content/common/swapped_out_messages.h"
 
 #include "content/common/view_messages.h"
 #include "content/public/common/content_client.h"
 
 namespace content {
 
@@ skipping 16 matching lines @@
       break;
   }
 
   // Check with the embedder as well.
   ContentClient* client = GetContentClient();
   return client->CanSendWhileSwappedOut(msg);
 }
 
 bool SwappedOutMessages::CanHandleWhileSwappedOut(
     const IPC::Message& msg) {
+  // We must allow all synchronous IPC messages to be processed, or else
+  // the renderer process will become stuck and won't respond to future
+  // navigations.
+  if (msg.is_sync())
+    return true;
+
   // Any message the renderer is allowed to send while swapped out should
   // be handled by the browser.
   if (CanSendWhileSwappedOut(&msg))
     return true;
 
   // We drop most other messages that arrive from a swapped out renderer.
   // However, some are important (e.g., ACKs) for keeping the browser and
   // renderer state consistent in case we later return to the renderer.
   switch (msg.type()) {
     // Sends an ACK.
@@ skipping 26 matching lines @@
     default:
       break;
   }
 
   // Check with the embedder as well.
   ContentClient* client = GetContentClient();
   return client->CanHandleWhileSwappedOut(msg);
 }
 
 }  // namespace content