[Smart Lock] Add a private API to show an error bubble anchored to the Smart Lock app window.

chrome/common/extensions/api/easy_unlock_private.idl

 // 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.
 
 // <code>chrome.easyUnlockPrivate</code> API that provides hooks to Chrome to
 // be used by Easy Unlock component app.
 namespace easyUnlockPrivate {
   // Signature algorithms supported by the crypto library methods used by
   // Easy Unlock.
   enum SignatureType {
@@ skipping 130 matching lines @@
 
     // Whether the user is logged in. If not logged in, the app is running on
     // the signin screen.
     boolean loggedIn;
 
     // Whether all data needed to use Easy unlock service has been loaded for
     // the user.
     boolean dataReady;
   };
 
+  // A range.
+  dictionary Range {
+    long start;
+    long end;
+  };
+
+  // A rectangle.
+  dictionary Rect {
+    long left;
+    long top;
+    long width;
+    long height;
+  };
+
   // Callback for crypto methods that return a single array buffer.
   callback DataCallback = void(optional ArrayBuffer data);
 
   // An empty callback used purely for signalling success vs. failure.
   callback EmptyCallback = void();
 
   // Callback for the getStrings() method.
   callback GetStringsCallback = void(object strings);
 
   // Callback for method that generates an encryption key pair.
@@ skipping 147 matching lines @@
     // success, the user session will be started.
     static void trySignInSecret(ArrayBuffer signInSecret,
                                 EmptyCallback callback);
 
     // Retrieves information about the user associated with the Easy unlock
     // service.
     static void getUserInfo(GetUserInfoCallback callback);
 
     // Gets the user's profile image as a bitmap.
     static void getUserImage(DataCallback callback);
+
+    // Shows an error bubble with the given |message|, anchored to the given
+    // |anchorRect|. If the |link_range| is non-empty, renders the text within
+    // the |message| that is contained in the |link_range| as a link with the
+    // given |link_target| URL.
+    static void showErrorBubble(DOMString message,
+                                Range link_range,
+                                DOMString link_target,
+                                Rect anchorRect);
   };
 
   interface Events {
     // Event fired when the data for the user currently associated with
     // Easy unlock service is updated.
     // |userInfo| The updated user information.
     static void onUserInfoUpdated(UserInfo userInfo);
   };
 };