Let the browser know about the renderer's page id assignments, even if the renderer is swapped out.

content/common/swapped_out_messages.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 "content/common/swapped_out_messages.h"
 
 #include "content/common/accessibility_messages.h"
 #include "content/common/frame_messages.h"
 #include "content/common/input_messages.h"
 #include "content/common/view_messages.h"
@@ skipping 26 matching lines @@
     case FrameHostMsg_BeforeUnload_ACK::ID:
     case FrameHostMsg_SwapOut_ACK::ID:
     // Frame detach must occur after the RenderView has swapped out.
     case FrameHostMsg_Detach::ID:
     case FrameHostMsg_DomOperationResponse::ID:
     case FrameHostMsg_CompositorFrameSwappedACK::ID:
     case FrameHostMsg_ReclaimCompositorResources::ID:
     // Input events propagate from parent to child.
     case FrameHostMsg_ForwardInputEvent::ID:
     case FrameHostMsg_InitializeChildFrame::ID:
+    // The browser should always have an accurate mirror of the renderer's
+    // notion of the current page id.
+    case FrameHostMsg_DidAssignPageId::ID:
       return true;
     default:
       break;
   }
 
   // Check with the embedder as well.
   ContentClient* client = GetContentClient();
   return client->CanSendWhileSwappedOut(msg);
 }
 
@@ skipping 30 matching lines @@
     case AccessibilityHostMsg_Events::ID:
       return true;
     default:
       break;
   }
 
   return false;
 }
 
 }  // namespace content