[Offline pages] Making sure reload snackbar is multiline when necessary

This patch makes sure it is possible to show a complete message related
to the offline page reload. This means splitting the message in two
lines when necessary.

BUG=594986

Review URL: https://codereview.chromium.org/1820903003

Cr-Commit-Position: refs/heads/master@{#382457}
1 file changed