Steps to reproduce: 
1. Launch ios_web_view_shell
2. Open some page
3. Press home button
4. Kill the app
5. Restart the app

Observed behavior: 
The previously opened page is shown briefly, but then the web view becomes blank.

Expected behavior: 
The previously opened page is kept shown.

Notes:
After state restoration, looks like CRWWebControllerContainer has no subviews, where it should contain the web view.

//src/ios/web_view/test/web_view_restorable_state_inttest passes, so I guess the WebState itself is correctly restored, but the views are not restored.