Able to reproduce the issue on chrome reported version# 68.0.3440.106 and on latest chrome# 71.0.3542.0 using Windows-10, Mac 10.13.1. As this issue is seen from M-68(from the introduction of #enable-emoji-context-menu flag), hence considering this issue as Non-Regression and marking it as Untriaged.
Note: Issue is specific to Windows and Mac.

Thanks!

FYI - on Windows, the keyboard shortcut to invoke the emoji picker is both "Win + :" and "Win + ." but the ":" key is more difficult to select on some keyboard locales, so displaying "Win + ." in the context menu for all languages is preferred

Mathieu - assigning to you for now but feel free to reassign to Ramya if need be. Note that for Mac we had the accelerator but it's disappeared so need to look into why.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d6bf1fc78657ddd780e174fdc5c2e5733ffb8893

commit d6bf1fc78657ddd780e174fdc5c2e5733ffb8893
Author: Mathieu Perreault <mathp@chromium.org>
Date: Fri Sep 21 19:14:06 2018

[Emoji] Add accelerator (shortcut key) for the Emoji Panel on Windows.

On Windows, assigns an accelerator to the Context Menu command that shows
the Emoji panel, both for the native Textfield's context menu and the
render_view's context menu.

The shortcut is "Win" + "Period"

Bug:  880653 
Change-Id: Ic6f41762c5903c2984bce93a5ac3185dc41e7199
Reviewed-on: https://chromium-review.googlesource.com/1235220
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Michael Wasserman <msw@chromium.org>
Commit-Queue: Mathieu Perreault <mathp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#593288}
[modify] https://crrev.com/d6bf1fc78657ddd780e174fdc5c2e5733ffb8893/chrome/browser/ui/views/renderer_context_menu/render_view_context_menu_views.cc
[modify] https://crrev.com/d6bf1fc78657ddd780e174fdc5c2e5733ffb8893/ui/base/accelerators/accelerator.cc
[modify] https://crrev.com/d6bf1fc78657ddd780e174fdc5c2e5733ffb8893/ui/strings/ui_strings.grd
[modify] https://crrev.com/d6bf1fc78657ddd780e174fdc5c2e5733ffb8893/ui/views/controls/textfield/textfield.cc
[modify] https://crrev.com/d6bf1fc78657ddd780e174fdc5c2e5733ffb8893/ui/views/controls/views_text_services_context_menu.h
[modify] https://crrev.com/d6bf1fc78657ddd780e174fdc5c2e5733ffb8893/ui/views/controls/views_text_services_context_menu_base.cc
[modify] https://crrev.com/d6bf1fc78657ddd780e174fdc5c2e5733ffb8893/ui/views/controls/views_text_services_context_menu_base.h

Able to reproduce the issue on chrome reported version# 68.0.3440.106 using Windows-10 and Mac 10.12.6. Verified the fix on chrome version# 71.0.3559.0 using Windows-10(i.e., Able to see shortcut hint as "Win+Period") but on Mac OS issue is still seen(i.e., short cut hint for "Emoji & Symbols" is not seen).

@Mathieu Perreault: Please find the above information and attached screenshots for your reference and help us in confirming the fix on Mac OS.

Thanks!

Deleted: 880653 - Mac.png 172 KB

	880653 - Mac.png 172 KB View Download

Deleted: 880653 - Windows.png 173 KB

	880653 - Windows.png 173 KB View Download

Thanks, behavior is correct on Mac.