PasswordStore: Clean up expectations about rewriting vectors of forms

chrome/browser/password_manager/password_store_x.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_PASSWORD_MANAGER_PASSWORD_STORE_X_H_
 #define CHROME_BROWSER_PASSWORD_MANAGER_PASSWORD_STORE_X_H_
 
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 40 matching lines @@
     // delete in either direction.
     virtual bool RemoveLoginsCreatedBetween(
         base::Time delete_begin,
         base::Time delete_end,
         password_manager::PasswordStoreChangeList* changes) = 0;
     virtual bool RemoveLoginsSyncedBetween(
         base::Time delete_begin,
         base::Time delete_end,
         password_manager::PasswordStoreChangeList* changes) = 0;
 
+    // The three methods below overwrite |forms| with all stored credentials
+    // matching |form|, all stored non-blacklisted credentials, and all stored
+    // blacklisted credentials, respectively. On success, they return true.
     virtual bool GetLogins(const autofill::PasswordForm& form,
-                           ScopedVector<autofill::PasswordForm>* forms) = 0;
+                           ScopedVector<autofill::PasswordForm>* forms)
+        WARN_UNUSED_RESULT = 0;
     virtual bool GetAutofillableLogins(
-        ScopedVector<autofill::PasswordForm>* forms) = 0;
-    virtual bool GetBlacklistLogins(
-        ScopedVector<autofill::PasswordForm>* forms) = 0;
+        ScopedVector<autofill::PasswordForm>* forms) WARN_UNUSED_RESULT = 0;
+    virtual bool GetBlacklistLogins(ScopedVector<autofill::PasswordForm>* forms)
+        WARN_UNUSED_RESULT = 0;
   };
 
   // Takes ownership of |login_db| and |backend|. |backend| may be NULL in which
   // case this PasswordStoreX will act the same as PasswordStoreDefault.
   PasswordStoreX(scoped_refptr<base::SingleThreadTaskRunner> main_thread_runner,
                  scoped_refptr<base::SingleThreadTaskRunner> db_thread_runner,
                  scoped_ptr<password_manager::LoginDatabase> login_db,
                  NativeBackend* backend);
 
  private:
@@ skipping 45 matching lines @@
   // Whether we should allow falling back to the default store. If there is
   // nothing to migrate, then the first attempt to use the native store will
   // be the first time we try to use it and we should allow falling back. If
   // we have migrated successfully, then we do not allow falling back.
   bool allow_fallback_;
 
   DISALLOW_COPY_AND_ASSIGN(PasswordStoreX);
 };
 
 #endif  // CHROME_BROWSER_PASSWORD_MANAGER_PASSWORD_STORE_X_H_