[Sync] Implement keystore migration support.

sync/test/fake_sync_encryption_handler.cc

Index: sync/test/fake_sync_encryption_handler.cc
diff --git a/sync/test/fake_sync_encryption_handler.cc b/sync/test/fake_sync_encryption_handler.cc
index 1dbdf8b75861c3fe6ad930af409cb9971622903f..3cf09081ee2399ce6a13f9ba7688811b658f53f1 100644
--- a/sync/test/fake_sync_encryption_handler.cc
+++ b/sync/test/fake_sync_encryption_handler.cc
@@ -26,13 +26,14 @@ void FakeSyncEncryptionHandler::ApplyNigoriUpdate(
     syncable::BaseTransaction* const trans) {
   if (nigori.encrypt_everything())
     EnableEncryptEverything();
-  if (nigori.using_explicit_passphrase())
+  if (nigori.frozen_keybag())
     passphrase_state_ = CUSTOM_PASSPHRASE;
 
-  if (cryptographer_.CanDecrypt(nigori.encrypted()))
-    cryptographer_.InstallKeys(nigori.encrypted());
-  else if (nigori.has_encrypted())
-    cryptographer_.SetPendingKeys(nigori.encrypted());
+  // TODO(zea): consider adding fake support for migration.
+  if (cryptographer_.CanDecrypt(nigori.encryption_keybag()))
+    cryptographer_.InstallKeys(nigori.encryption_keybag());
+  else if (nigori.has_encryption_keybag())
+    cryptographer_.SetPendingKeys(nigori.encryption_keybag());
 
   if (cryptographer_.has_pending_keys()) {
     DVLOG(1) << "OnPassPhraseRequired Sent";