cros: Added a new function to quick unlock api for checking unfinished pins.

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(jdufault): Add more quick unlock modes, such as a pattern unlock.
   enum QuickUnlockMode {
     PIN
   };
 
+  enum PinState {
+    GOOD,
+    SHORTER_THAN_MIN,
+    LONGER_THAN_MAX,
+    ALL_SAME_NUM,
+    INCREASING
+  };
+
   callback BooleanResultCallback = void (boolean value);
   callback ModesCallback = void (QuickUnlockMode[] modes);
+  callback PinStatesCallback = void (PinState state);
 
   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);
 
+    // Returns whether the pin can be used or if there is issue with the choice
+    // of pin.
+    static void getUsablePin(DOMString attemptedPassword,

[jdufault, 2016/09/29 19:36:52]

Note the difference between how password and credential are used in this file.

This API needs to account for two additional things:

- Adding a new quick unlock mode
- Exposing information to the user (such as minimum length).

We should reach out to UI folks and decide if we need to expose specific
information, because that will change the shape of the API. For example, it may
be okay to say "This PIN is too short" instead of "Enter a PIN between 4 and 6
digits".

What about something along these lines? We could drop CredentialRequirement if
we don't need the specific policy information.

  enum CredentialRequirementFailure {
    TOO_SHORT,
    TOO_LONG,
    TOO_WEAK
  };
  
  dictionary CredentialRequirement {
    CredentialRequirementFailure[] failures;
    Number? minLength;
    Number? maxLength;
  };

  callback CredentialRequirementCallback =
      void (CredentialRequirement requirement);

  static void isCredentialUsable(
      QuickUnlockMode mode,
      DOMString credential,
      CredentialRequirementCallback onComplete);

[sammiequon, 2016/09/30 00:35:08]

Done.

+                             PinStatesCallback onComplete);
+
     // Update the set of quick unlock modes that are currently active/enabled.
     // |accountPassword|: The password associated with the account (e.g. the
     // GAIA password). This is required to change the quick unlock credentials.
     // |modes|: The quick unlock modes that should be active.
     // |credentials|: The associated credential for each mode. To keep
     // the credential the same for the associated mode, pass an empty string.
     // |onComplete|: Called with true if the quick unlock state was updated,
     // false otherwise. The update is treated as a single atomic operation.
     static void setModes(DOMString accountPassword,
                          QuickUnlockMode[] modes, DOMString[] credentials,
                          BooleanResultCallback onComplete);
   };
 
   interface Events {
     // Called after the active set of quick unlock modes has changed.
     // |activeModes|: The set of quick unlock modes which are now active.
     static void onActiveModesChanged(QuickUnlockMode[] activeModes);
   };
 };