mojo api for view based lockscreen

ash/public/interfaces/lock_screen.mojom

Index: ash/public/interfaces/lock_screen.mojom
diff --git a/ash/public/interfaces/lock_screen.mojom b/ash/public/interfaces/lock_screen.mojom
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+// Copyright 2017 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.
+
+module ash.mojom;
+
+import "components/signin/public/interfaces/account_id.mojom";
+
+// Allows clients (e.g. Chrome browser) to control the ash lock screen.
+interface LockScreen {
+  // Sets the client interface.
+  SetClient(LockScreenClient client);
+
+  // Requests to show error message in the ash lock screen.
+  // TODO(xiaoyinh): login_attempts is probabaly not needed from chrome,
+  // remove it when we start to count the login attempts in ash lock screen.
+  // |login_attempts|: The number of the login authentication attempts.
+  // |error_text|:     The error text to be shown in lock screen.
+  // |help_link_text|: The help link to be shown in lock screen.
+  // |help_topic_id|:  The id of the help app topic regarding this error.
+  ShowErrorMessage(int32 login_attempts,
+                   string error_text,
+                   string help_link_text,
+                   int32 help_topic_id);
+
+  // Requests to close any displayed error messages in ash lock screen.
+  ClearErrors();
+};
+
+// Allows ash lock screen to control a client (e.g. Chrome browser). Requests
+// often involve preferences or talk to cryptohome that is not available to ash.
+interface LockScreenClient {
+  // Request user authentication in chrome.
+  // If auth succeeds:
+  // chrome will hide the lock screen and clear any displayed error messages.
+  // If auth fails:
+  // chrome will request lock screen to show error messages.
+  // |account_id|:           The account id of the user we are authenticating.
+  // |hashed_password|:      The hashed password of the user.
+  // |authenticated_by_pin|: True if we are using pin to authenticate.
+  AuthenticateUser(signin.mojom.AccountId account_id,
+                   string hashed_password,
+	           bool authenticated_by_pin);
+};