Add finch config to prefer using VAPID over Sync

Bug: 1081819
Change-Id: Ia241e28e60142e757a820f533e828345d54ce366
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2196666
Commit-Queue: Alex Chau <[email protected]>
Reviewed-by: Michael van Ouwerkerk <[email protected]>
Cr-Commit-Position: refs/heads/master@{#768288}
diff --git a/chrome/browser/sharing/features.h b/chrome/browser/sharing/features.h
index db0ff1a..3acb082 100644
--- a/chrome/browser/sharing/features.h
+++ b/chrome/browser/sharing/features.h
@@ -54,4 +54,7 @@
 // Feature flag for sending sharing message via Sync.
 extern const base::Feature kSharingSendViaSync;
 
+// Feature flag for prefer sending sharing message using VAPID.
+extern const base::Feature kSharingPreferVapid;
+
 #endif  // CHROME_BROWSER_SHARING_FEATURES_H_