GitLab

This CL adds :
1 - Try now button is shown on the video player for certain tutorials
for whom the steps are defined.
2 - The video player launches ChromeTabbedActivity and stores the
 tutorial info in a temporary tracker VideoTutorialTryNowTracker.
3 - NewTabPageLayout checks the tracker in onWindowVisibilityChanged()
 and shows IPH on search box for search or voice search.
4 - ToolbarButtonInProductHelpController checks the tracker on resume,
 and shows downloads tutorial IPH if any.
5 - IPHCommand and UserEducationHelper were modified to handle an
 "always show IPH", which is checked by checking if featureName is null.
 In that scenario, any call to feature engagement Tracker is skipped.
6- Some small fixs on layout XML file.

UX: https://docs.google.com/presentation/d/1jszfqrCLufu0mskWls6unqilpmG3PoHKdySsf4uF-eo/edit#slide=id.g8a320d9435_2_550

Bug: 1133637
Change-Id: I65262d0e2e85cb15f97971d039e47905983e90df
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2439781
Commit-Queue: Shakti Sahu <shaktisahu@chromium.org>
Reviewed-by: David Trainor <dtrainor@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815967}