Don't process messages sent to dead routing ids.

content/test/web_contents_observer_sanity_checker.cc

Index: content/test/web_contents_observer_sanity_checker.cc
diff --git a/content/test/web_contents_observer_sanity_checker.cc b/content/test/web_contents_observer_sanity_checker.cc
index 8ac2dd0f199b84158997e211d665083696d95ce3..24b8ac945d9f258084c9f1923390a4d4c8a1312b 100644
--- a/content/test/web_contents_observer_sanity_checker.cc
+++ b/content/test/web_contents_observer_sanity_checker.cc
@@ -317,11 +317,9 @@ bool WebContentsObserverSanityChecker::OnMessageReceived(
   // FrameHostMsg_RenderProcessGone is special internal IPC message that
   // should not be leaking outside of RenderFrameHost.
   CHECK(message.type() != FrameHostMsg_RenderProcessGone::ID);
+  CHECK(render_frame_host->IsRenderFrameLive());
 
-#if !defined(OS_MACOSX)
-// TODO(avi): Disabled because of http://crbug.com/445054
   AssertRenderFrameExists(render_frame_host);
-#endif
   return false;
 }