Reland "Add UMA for sync favicons in recently closed tabs menu"

This is a reland of 5432d3b6be72f04ea14518bd400e3b1247124589

Original change's description:
> Add  UMA for sync favicons in recently closed tabs menu
>
> We add metrics to evaluate sync's usefulness in helping obtain favicons
> for the recently closed tabs menu.
>
> Bug: 948109
> Change-Id: I88958d41925dc9bab93d1714a0b4e56e88b10c17
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1564995
> Commit-Queue: Victor Vianna <victorvianna@google.com>
> Reviewed-by: Peter Kasting <pkasting@chromium.org>
> Reviewed-by: Alex Ilin <alexilin@chromium.org>
> Reviewed-by: Peter Kotwicz <pkotwicz@chromium.org>
> Reviewed-by: Dan Beam <dbeam@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#652119}

TBR=pkasting@chromium.org
TBR=pkotwicz@chromium.org
TBR=alexilin@chromium.org

Bug: 948109
Change-Id: If6d6822379be38a8e0b0b18a2ffd0cc5e5497c43
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1573622
Reviewed-by: Jan Krcal <jkrcal@chromium.org>
Commit-Queue: Victor Vianna <victorvianna@google.com>
Cr-Commit-Position: refs/heads/master@{#653155}
4 files changed