[Sync] Refactor passphrase state handling

chrome/browser/sync/glue/sync_backend_host.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_H_
 #define CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 436 matching lines @@
 
   // Invoked when the set of encrypted types or the encrypt
   // everything flag changes.
   void NotifyEncryptedTypesChanged(
       syncer::ModelTypeSet encrypted_types,
       bool encrypt_everything);
 
   // Invoked when sync finishes encrypting new datatypes.
   void NotifyEncryptionComplete();
 
+  // Invoked when the passphrase state has changed. Caches the passphrase state
+  // for later use on the UI thread.
+  void HandlePassphraseStateChangedOnFrontendLoop(
+      syncer::PassphraseState state);
+
   void HandleStopSyncingPermanentlyOnFrontendLoop();
 
   // Dispatched to from OnConnectionStatusChange to handle updating
   // frontend UI components.
   void HandleConnectionStatusChangeOnFrontendLoop(
       syncer::ConnectionStatus status);
 
   // Called when configuration of the Nigori node has completed as
   // part of the initialization process.
   void HandleNigoriConfigurationCompletedOnFrontendLoop(
@@ skipping 48 matching lines @@
   // We cache the cryptographer's pending keys whenever NotifyPassphraseRequired
   // is called. This way, before the UI calls SetDecryptionPassphrase on the
   // syncer, it can avoid the overhead of an asynchronous decryption call and
   // give the user immediate feedback about the passphrase entered by first
   // trying to decrypt the cached pending keys on the UI thread. Note that
   // SetDecryptionPassphrase can still fail after the cached pending keys are
   // successfully decrypted if the pending keys have changed since the time they
   // were cached.
   sync_pb::EncryptedData cached_pending_keys_;
 
+  // The state of the passphrase required to decrypt the bag of encryption keys
+  // in the nigori node. Updated whenever a new nigori node arrives or the user
+  // manually changes their passphrase state. Cached so we can synchronously
+  // check it from the UI thread.
+  syncer::PassphraseState cached_passphrase_state_;
+
   // UI-thread cache of the last SyncSessionSnapshot received from syncapi.
   syncer::sessions::SyncSessionSnapshot last_snapshot_;
 
   // Temporary holder for the javascript backend. Set by
   // HandleSyncManagerInitializationOnFrontendLoop, and consumed when we pass
   // it via OnBackendInitialized in the final state of
   // HandleInitializationCompletedOnFrontendLoop.
   syncer::WeakHandle<syncer::JsBackend> js_backend_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncBackendHost);
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_H_