[Sync] Adding integration tests for USS encryption and fixing a worker bug.

components/sync/engine/sync_encryption_handler.h

Index: components/sync/engine/sync_encryption_handler.h
diff --git a/components/sync/engine/sync_encryption_handler.h b/components/sync/engine/sync_encryption_handler.h
index 52c5750f516fa7089f8c12b0d8c8ca8712419de5..db6564532518daa5b645617f2d7d3634b08ed02a 100644
--- a/components/sync/engine/sync_encryption_handler.h
+++ b/components/sync/engine/sync_encryption_handler.h
@@ -62,10 +62,11 @@ class SyncEncryptionHandler {
     virtual void OnPassphraseRequired(
         PassphraseRequiredReason reason,
         const sync_pb::EncryptedData& pending_keys) = 0;
+
     // Called when the passphrase provided by the user has been accepted and is
     // now used to encrypt sync data.
-
     virtual void OnPassphraseAccepted() = 0;
+
     // |bootstrap_token| is an opaque base64 encoded representation of the key
     // generated by the current passphrase, and is provided to the observer for
     // persistence purposes and use in a future initialization of sync (e.g.