[Payment] Add the OS field to payment OWNERS file

Change-Id: I36ca73f222600f47b55298202354eb66279c00b8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2288830Reviewed-by: Danyao Wang <danyao@chromium.org>
Commit-Queue: Liquan (Max) Gu <maxlg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#786513}

chrome/android/java/src/org/chromium/chrome/browser/payments/OWNERS

 # TEAM: payments-dev@chromium.org
 # COMPONENT: UI>Browser>Payments
+# OS: Android
 
 file://components/payments/OWNERS
 

components/payments/content/android/java/src/org/chromium/components/payments/OWNERS

 # TEAM: payments-dev@chromium.org
 # COMPONENT: UI>Browser>Payments
+# OS: Android
 
 file://components/payments/OWNERS