[Global Media Controls] RegisterHotKey for GlobalMediaKeysListenerWin

This CL refactors the GlobalMediaKeysListenerWin to use RegisterHotKey
to receive media key input instead of using a low-level keyboard hook.

This has a few key advantages:
- No need for separate, dedicated thread to avoid key input delays
- Will be cleaner to use with GlobalShortcutListenerWin since we need
  to support extension shortcut listeners alongside the upcoming
  HardwareKeyMediaController
- Will play more nicely with other native Windows applications (albeit
  at the cost of being slightly less powerful)

Bug: 902379
Change-Id: I055df46a0231a4abb08cf3786fc58140c2a47241
Reviewed-on: https://chromium-review.googlesource.com/c/1401363
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Tommy Steimel <steimel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#621922}
12 files changed