Waiting on https://chromium-review.googlesource.com/c/chromium/src/+/1147157

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/34b5e629fdf85cda487373c2b178d23de8f7892b

commit 34b5e629fdf85cda487373c2b178d23de8f7892b
Author: Leonard Grey <lgrey@chromium.org>
Date: Mon Jul 30 19:05:55 2018

Mac: Create share submenu when initially building main menu

When the native share menu was an experiment, we needed to replace the
Email Page Location menu item at runtime if the experiment was enabled.

It's now been enabled for a while, so this change removes the Email
Page Location menu item entirely and creates the Share menu item as
part of the initial menu creation.

Also removes the experiment infrastructure for share menu.

Bug:  770804 
Change-Id: If5f17c213ffb185b461ee4e766423c647cb43e18
Reviewed-on: https://chromium-review.googlesource.com/1152007
Commit-Queue: Leonard Grey <lgrey@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579110}
[modify] https://crrev.com/34b5e629fdf85cda487373c2b178d23de8f7892b/chrome/app/generated_resources.grd
[modify] https://crrev.com/34b5e629fdf85cda487373c2b178d23de8f7892b/chrome/browser/about_flags.cc
[modify] https://crrev.com/34b5e629fdf85cda487373c2b178d23de8f7892b/chrome/browser/app_controller_mac.mm
[modify] https://crrev.com/34b5e629fdf85cda487373c2b178d23de8f7892b/chrome/browser/flag_descriptions.cc
[modify] https://crrev.com/34b5e629fdf85cda487373c2b178d23de8f7892b/chrome/browser/flag_descriptions.h
[modify] https://crrev.com/34b5e629fdf85cda487373c2b178d23de8f7892b/chrome/browser/ui/cocoa/main_menu_builder.mm
[modify] https://crrev.com/34b5e629fdf85cda487373c2b178d23de8f7892b/chrome/common/chrome_features.cc
[modify] https://crrev.com/34b5e629fdf85cda487373c2b178d23de8f7892b/chrome/common/chrome_features.h
[modify] https://crrev.com/34b5e629fdf85cda487373c2b178d23de8f7892b/tools/gritsettings/startup_resources_mac.txt