Add perf histogram and tests for inline signin

chrome/browser/resources/gaia_auth_host/gaia_auth_host.js

 // Copyright 2013 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.
 
 /**
  * @fileoverview An UI component to host gaia auth extension in an iframe.
  * After the component binds with an iframe, call its {@code load} to start the
  * authentication flow. There are two events would be raised after this point:
  * a 'ready' event when the authentication UI is ready to use and a 'completed'
  * event when the authentication is completed successfully. If caller is
@@ skipping 324 matching lines @@
         this.password_ = msg.password;
         this.chooseWhatToSync_ = msg.chooseWhatToSync;
         return;
       }
 
       if (!this.isAuthExtMessage_(e))
         return;
 
       if (msg.method == 'loginUILoaded') {
         cr.dispatchSimpleEvent(this, 'ready');
+        // Declare __login_ui_initialized in window object so it could be read
+        // directly in telemetry tests.
+        if (msg.load_start_ts && !window.__login_ui_initialized) {
+          chrome.send('loginUIInitialized',
+                      [msg.load_start_ts, msg.load_stop_ts]);
+          window.__login_ui_initialized = true;
+        }
         return;
       }
 
       if (/^complete(Login|Authentication)$|^offlineLogin$/.test(msg.method)) {
         if (!msg.email && !this.email_ && !msg.skipForNow) {
           var msg = {method: 'redirectToSignin'};
           this.frame_.contentWindow.postMessage(msg, AUTH_URL_BASE);
           return;
         }
         this.onAuthSuccess_({email: msg.email || this.email_,
@@ skipping 81 matching lines @@
 
   GaiaAuthHost.SUPPORTED_PARAMS = SUPPORTED_PARAMS;
   GaiaAuthHost.LOCALIZED_STRING_PARAMS = LOCALIZED_STRING_PARAMS;
   GaiaAuthHost.AuthMode = AuthMode;
   GaiaAuthHost.AuthFlow = AuthFlow;
 
   return {
     GaiaAuthHost: GaiaAuthHost
   };
 });