Fix for non-live RenderFramehosts incorrectly marked as live.

I noticed that FrameTreeNodes that contain inner WebContentses have
RenderFrameHosts that are marked "live" (for the purposes of
RenderFrameHost::IsRenderFrameHostLive()) even though they do not have any
associated RenderFrames. This patch fixes that.

CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_site_isolation

Review-Url: https://codereview.chromium.org/2346673002
Cr-Commit-Position: refs/heads/master@{#419150}

content/browser/frame_host/render_frame_host_manager.cc

@@ -1842,6 +1842,9 @@ void RenderFrameHostManager::CreateOuterDelegateProxy(
       false /* is_loading */,
       render_frame_host->frame_tree_node()->current_replication_state()));
   proxy->set_render_frame_proxy_created(true);
+
+  // There is no longer a RenderFrame associated with this RenderFrameHost.
+  render_frame_host->SetRenderFrameCreated(false);
 }
 
 void RenderFrameHostManager::SetRWHViewForInnerContents(