DevTools security panel: prompt user to reload for mixed requests
When there are no network requests recorded, prompt the user to reload,
instead of making them click over to the network panel where they are
prompted to reload.
BUG=
648646
Committed:
https://crrev.com/81e423ee392a3b383431c906b6a2767fcfdf0764
Cr-Commit-Position: refs/heads/master@{#427240}