Implement the private API for quick unlock.

chrome/common/extensions/api/quick_unlock_private.idl

+// Copyright 2016 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.
+
+// Use the <code>chrome.quickUnlockPrivate</code> API to change the active quick
+// unlock modes and to change their respective credentials.
+//
+// Quick unlock only supports unlocking an account that has already been signed
+// in.
+//
+// The quick unlock authentication facilities are not available through this
+// API; they are built directly into the lock screen.
+
+[platforms=("chromeos"),
+ implemented_in="chrome/browser/chromeos/extensions/quick_unlock_private/quick_unlock_private_api.h"]
+namespace quickUnlockPrivate {
+  // TODO: Add more quick unlock modes, such as a pattern unlock.
+  enum QuickUnlockMode {
+    PIN
+  };
+
+  callback BooleanResultCallback = void (boolean value);
+  callback ModesCallback = void (QuickUnlockMode[] modes);
+
+  interface Functions {
+    // Returns the set of quick unlock modes that are available for the user to
+    // use. Some quick unlock modes may be disabled by policy.
+    static void getAvailableModes(ModesCallback onComplete);
+
+    // Returns the quick unlock modes that are currently enabled and usable on
+    // the lock screen.
+    static void getActiveModes(ModesCallback onComplete);
+
+    // Update the set of quick unlock modes that are currently active/enabled.
+    // |accountPassword| is the password associated with the account (e.g. the

[Devlin, 2016/06/01 17:44:13]

nit: preferred syntax would be
|<var>|: description
e.g.
|accountPassword|: The password associated...

(We parse this out into descriptions for each variable, and it doesn't make
sense to have a description that begins with "is")

[jdufault, 2016/06/03 23:13:16]

Done.

+    // GAIA password) and is required to change the quick unlock credentials.
+    // |modes| is the quick unlock modes that should be active.
+    // |credentials| contains the associated credential for each mode. To keep
+    // the credential the same for one of the modes, pass an empty string.
+    // |onComplete| is called with true if the quick unlock state was updated,
+    // false otherwise. The update is treated as a single atomic operation.
+    // chrome.runtime.lastError will be set if the API was used incorrectly.

[Devlin, 2016/06/01 17:44:13]

This (lastError comment) is standard for all APIs.  I'd remove it.

[jdufault, 2016/06/03 23:13:16]

Done.

+    static void setModes(DOMString accountPassword,
+                         QuickUnlockMode[] modes, DOMString[] credentials,
+                         BooleanResultCallback onComplete);
+  };
+
+  interface Events {
+    // Called after the active set of quick unlock modes has changed.

[Devlin, 2016/06/01 17:44:13]

Might be worth specifying that newModes is the collection of all currentModes,
rather than the delta between old and current.

[jdufault, 2016/06/03 23:13:16]

Done.

+    static void onActiveModesChanged(QuickUnlockMode[] newModes);
+  };
+};