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When navigating to about:version/?show-variations-cmd an additional section
will appear showing complete set of client's variations in the command line
formatting that can be used to reproduce the same exact state of variations.
The displayed info contains all the trials including not activated ones
marked by '*' along with the corresponding group assignment.
It will also contain enabled and disabled features where the ones that should
use the default value will be marked with '*'(e.g. expired trials).
Trials that are unforcable through command line will be shown but warning will
be shown when processing the command line input with unforcable trial.
This CL doesn't cover iOS.

As the displayed text is huge I also changed the width of the text in the
about:version page (not mobile) to be 60% of the page with a minimum of 800px
as it used to be.

Bug: 694675
TEST=unit test, manual testing
1. run chrome with --fake-variations-channel=beta
2. copying command line input from about:version/?show-variations-cmd
3. run chrome without channel but with command line input copied in step 2.
4. confirm about:version/?show-variations-cmd page shows the same info

Change-Id: Ie73174bd5bd1a02baa75cd3294fd36cf63b3c923
Reviewed-on: https://chromium-review.googlesource.com/865286
Commit-Queue: Gayane Petrosyan <gayane@chromium.org>
Reviewed-by: Dave Schuyler <dschuyler@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533742}