Open the LoginDatabase on the DB thread, not the UI thread.

components/password_manager/core/browser/password_store.h

 // Copyright 2014 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 COMPONENTS_PASSWORD_MANAGER_CORE_BROWSER_PASSWORD_STORE_H_
 #define COMPONENTS_PASSWORD_MANAGER_CORE_BROWSER_PASSWORD_STORE_H_
 
 #include <vector>
 
 #include "base/callback.h"
@@ skipping 33 matching lines @@
 
 namespace password_manager {
 
 class PasswordManagerClient;
 class PasswordStoreConsumer;
 class PasswordSyncableService;
 
 // Interface for storing form passwords in a platform-specific secure way.
 // The login request/manipulation API is not threadsafe and must be used
 // from the UI thread.
+// Implementations, however, should carry out most tasks asynchronously on the
+// the DB thread: the base class provides functionality to facilitate this.
+// I/O heavy initialization should also be performed asynchronously on the DB
+// thread. If deferred initialization fails, all subsequent method calls should
+// fail without side effects, return no data, and trigger no notifications.
 // PasswordStoreSync is a hidden base class because only PasswordSyncableService
 // needs to access these methods.
 class PasswordStore : protected PasswordStoreSync,
                       public base::RefCountedThreadSafe<PasswordStore> {
  public:
   // Whether or not it's acceptable for Chrome to request access to locked
   // passwords, which requires prompting the user for permission.
   enum AuthorizationPromptPolicy {
     ALLOW_PROMPT,
     DISALLOW_PROMPT
@@ skipping 236 matching lines @@
   scoped_ptr<PasswordSyncableService> syncable_service_;
 
   bool shutdown_called_;
 
   DISALLOW_COPY_AND_ASSIGN(PasswordStore);
 };
 
 }  // namespace password_manager
 
 #endif  // COMPONENTS_PASSWORD_MANAGER_CORE_BROWSER_PASSWORD_STORE_H_