Remove media/gpu from _NOT_CONVERTED_TO_MODERN_BIND_AND_CALLBACK

This is the list of directories excluded from presubmit checks
for base::Bind, base::Closure, and base::Callback.

Bug: 1007807
Change-Id: I3709ef9dff97beabc02c9cc4d90763bfe557b39c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2543445Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: David Bienvenu <davidbienvenu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#828075}

PRESUBMIT.py

@@ -381,7 +381,6 @@ _NOT_CONVERTED_TO_MODERN_BIND_AND_CALLBACK = '|'.join((
   '^media/blink/',
   '^media/cast/',
   '^media/cdm/',
-  '^media/gpu/',
   '^media/mojo/',
   '^net/http/',
   '^net/url_request/',