GitLab

Adds the IPH that points to the data saver preview infobar.  This
includes three main changes:
- Adding support for determining which kind of infobar is showing in
Java.
- Hooking up the info bar show code to log an event saying it was shown.
- Hooking up the info bar show code to a function which can pick (if
any) a feature and string to show which will point to that infobar.

BUG=710648

Review-Url: https://codereview.chromium.org/2815653003
Cr-Commit-Position: refs/heads/master@{#467935}