Convert background_fetch to new Mojo types

This CL converts the methods overridden from
blink::mojom::BackgroundFetchRegistrationService
in BackgroundFetchRegistrationServiceImpl and
the related methods to new Mojo types.

Bug: 955171, 978694
Change-Id: If34cc1c7d752d9b5b16b662e807b95357ca71ac3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1735240
Reviewed-by: Ken Rockot <[email protected]>
Reviewed-by: Kinuko Yasuda <[email protected]>
Commit-Queue: Julie Kim(OoO until Aug 8th) <[email protected]>
Cr-Commit-Position: refs/heads/master@{#685036}
diff --git a/content/browser/background_fetch/background_fetch_context.h b/content/browser/background_fetch/background_fetch_context.h
index 47645912a..20b9cfe9 100644
--- a/content/browser/background_fetch/background_fetch_context.h
+++ b/content/browser/background_fetch/background_fetch_context.h
@@ -111,7 +111,8 @@
   // will unregister itself when the Mojo endpoint goes away.
   void AddRegistrationObserver(
       const std::string& unique_id,
-      blink::mojom::BackgroundFetchRegistrationObserverPtr observer);
+      mojo::PendingRemote<blink::mojom::BackgroundFetchRegistrationObserver>
+          observer);
 
   // Updates the title or icon of the Background Fetch identified by
   // |registration_id|. The |callback| will be invoked when the title has been