Add # COMPONENT: Internals>Cast>Providers as per suggested by mfoltz@

See https://tinyurl.com/yxau5sc4 for context.

Bug: 977050
Change-Id: I192c2ad0daab7ef35dbc24e669634caee810ff03
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1829248Reviewed-by: mark a. foltz <mfoltz@chromium.org>
Commit-Queue: mark a. foltz <mfoltz@chromium.org>
Auto-Submit: Eric Foo <efoo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#701200}

third_party/openscreen/OWNERS

@@ -2,4 +2,4 @@ mfoltz@chromium.org
 btolsch@chromium.org
 pthatcher@chromium.org
 
-# COMPONENT: Blink>PresentationAPI
+# COMPONENT: Internals>Cast>Providers