GMC: Update tooltip string

This CL updates the GMC toolbar button's tooltip string from "Global
Media Controls" to "Control your music, videos, and more"

Bug: 991271
Change-Id: Ie2554ac6102421e7f12f80b2dc64c16f9eeb4f2a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1758218Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Commit-Queue: Tommy Steimel <steimel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#688373}

chrome/app/global_media_controls_strings.grdp

@@ -2,6 +2,6 @@
 <!-- Global Media Controls-specific strings (included from generated_resources.grd). -->
 <grit-part>
   <message name="IDS_GLOBAL_MEDIA_CONTROLS_ICON_TOOLTIP_TEXT" desc="Tooltip for the Global Media Controls icon, which appears in the toolbar. The tooltip appears on mouseover of the icon.">
-   Global Media Controls
+   Control your music, videos, and more
   </message>
 </grit-part>