Properly recreate swapped out RenderView.

content/browser/frame_host/render_frame_host_manager.cc

Index: content/browser/frame_host/render_frame_host_manager.cc
diff --git a/content/browser/frame_host/render_frame_host_manager.cc b/content/browser/frame_host/render_frame_host_manager.cc
index e19b9fa3212da70629e2d0e8f8c9ed8b1fc4e978..b11364e69ff24a98af173e7343e875ffdb8cb5a5 100644
--- a/content/browser/frame_host/render_frame_host_manager.cc
+++ b/content/browser/frame_host/render_frame_host_manager.cc
@@ -913,6 +913,15 @@ void RenderFrameHostManager::DiscardUnusedFrame(
         render_frame_host->SwapOut(proxy, false);
 
       proxy->TakeFrameHostOwnership(render_frame_host.Pass());
+    } else {
+      // If |render_frame_host| is the RenderViewHost's main frame, it must
+      // be cleared, as it will be deleted at the end of this method.

[Charlie Reis, 2015/10/16 17:02:23]

s/, it must be cleared/, then the RenderViewHost must forget about it/

+      if (frame_tree_node_->IsMainFrame() &&
+          render_frame_host->render_view_host()->GetMainFrame() ==
+              render_frame_host.get()) {
+        render_frame_host->render_view_host()->set_main_frame_routing_id(
+            MSG_ROUTING_NONE);
+      }
     }
   }
 
@@ -1830,6 +1839,12 @@ scoped_ptr<RenderFrameHostImpl> RenderFrameHostManager::CreateRenderFrame(
     }
 
     if (frame_tree_node_->IsMainFrame()) {
+      if (!render_view_host->GetMainFrame()) {

[Charlie Reis, 2015/10/16 17:02:23]

What would happen if it had a main frame routing ID for a different frame, or a
non-existing frame?

+        CHECK(!render_view_host->is_active());
+        render_view_host->set_main_frame_routing_id(
+            new_render_frame_host->GetRoutingID());
+      }
+
       success = InitRenderView(render_view_host, proxy_routing_id);
 
       // If we are reusing the RenderViewHost and it doesn't already have a