Android: Extend ownership for android build files

Allow //src/build/android/OWNERS to own all gn-related files under
//src/chrome/android/.

Bug: None
Change-Id: Icbb98b2cef2869024045a736c2e5f1b21820b725
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1942876
Commit-Queue: Peter Wen <wnwen@chromium.org>
Reviewed-by: Eric Stevenson <estevenson@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Auto-Submit: Peter Wen <wnwen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720073}

chrome/android/OWNERS

@@ -14,12 +14,12 @@ per-file chrome_java_sources.gni=*
 per-file chrome_test_java_sources.gni=*
 per-file chrome_junit_test_java_sources.gni=*
 
-per-file BUILD.gn=estevenson@chromium.org
-per-file BUILD.gn=tiborg@chromium.org
-per-file BUILD.gn=wnwen@chromium.org
-# For VR Javatest changes
+# For VR Javatest changes.
 per-file BUILD.gn=bsheedy@chromium.org
 
+# Build-related files.
+per-file *.gn*=file://build/android/OWNERS
+
 # Translation artifacts:
 per-file *.xtb=file://tools/translation/TRANSLATION_OWNERS