Show a loading UI when waiting for the sync consent screen to be ready

Bug: 837577
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I709b737af4e8b77de40be4f2798681ffa45532b4
Reviewed-on: https://chromium-review.googlesource.com/1097948Reviewed-by: Alexander Alekseev <alemate@chromium.org>
Reviewed-by: Jacob Dufault <jdufault@chromium.org>
Commit-Queue: Xiaoyin Hu <xiaoyinh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567117}

chrome/browser/chromeos/login/screens/sync_consent_screen.cc

@@ -57,12 +57,15 @@ void SyncConsentScreen::Show() {
   }
 
   shown_ = true;
-  if (behavior_ == SyncScreenBehavior::SHOW) {
-    view_->Show();
-  } else {
-    // Wait for updates if not shown.
+  if (behavior_ != SyncScreenBehavior::SHOW) {
+    // Wait for updates and set the loading throbber to be visible.
+    view_->SetThrobberVisible(true /*visible*/);
     GetSyncService(profile_)->AddObserver(this);
   }
+  // Show the entire screen.
+  // If SyncScreenBehavior is show, this should show the sync consent screen.
+  // If SyncScreenBehavior is unknown, this should show the loading throbber.
+  view_->Show();
 }
 
 void SyncConsentScreen::Hide() {
@@ -152,7 +155,7 @@ void SyncConsentScreen::UpdateScreen() {
     Finish(ScreenExitCode::SYNC_CONSENT_FINISHED);
 
   if (behavior_ == SyncScreenBehavior::SHOW) {
-    view_->Show();
+    view_->SetThrobberVisible(false /*visible*/);
     GetSyncService(profile_)->RemoveObserver(this);
   }
 }

chrome/browser/chromeos/login/screens/sync_consent_screen_view.h

@@ -27,6 +27,10 @@ class SyncConsentScreenView {
 
   // Hides the contents of the screen.
   virtual void Hide() = 0;
+
+  // Controls if the loading throbber is visible. This is used when
+  // SyncScreenBehavior is unknown.
+  virtual void SetThrobberVisible(bool visible) = 0;
 };
 
 }  // namespace chromeos

chrome/browser/resources/chromeos/login/screen_sync_consent.html

 <!-- 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. -->
+<link rel="import" href="chrome://oobe/custom_elements.html">
 
 <div class="step right hidden" id="sync-consent" hidden>
   <sync-consent id="sync-consent-impl"></sync-consent>
+  <oobe-dialog id="sync-loading" role="dialog" no-header no-footer-padding
+      hidden>
+    <div class="footer flex layout vertical center center-justified">
+      <throbber-notice i18n-values="text:gaiaLoading">
+      </throbber-notice>
+    </div>
+  </oobe-dialog>
 </div>

chrome/browser/resources/chromeos/login/screen_sync_consent.js

@@ -8,7 +8,7 @@
 
 login.createScreen('SyncConsentScreen', 'sync-consent', function() {
   return {
-    EXTERNAL_API: ['onUserSyncPrefsKnown'],
+    EXTERNAL_API: ['onUserSyncPrefsKnown', 'setThrobberVisible'],
 
     /**
      * Returns the control which should receive initial focus.
@@ -25,6 +25,13 @@ login.createScreen('SyncConsentScreen', 'sync-consent', function() {
       Oobe.getInstance().headerHidden = true;
     },
 
+    /**
+     * Event handler that is invoked just before the screen is hidden.
+     */
+    onBeforeHide: function() {
+      this.setThrobberVisible(false /*visible*/);
+    },
+
     /**
      * This is called after resources are updated.
      */
@@ -40,5 +47,14 @@ login.createScreen('SyncConsentScreen', 'sync-consent', function() {
     onUserSyncPrefsKnown: function(sync_everything, is_managed) {
       $('sync-consent-impl').onUserSyncPrefsKnown(sync_everything, is_managed);
     },
+
+    /**
+     * This is called to show/hide the loading UI.
+     * @param {boolean} visible whether to show loading UI.
+     */
+    setThrobberVisible: function(visible) {
+      $('sync-loading').hidden = !visible;
+      $('sync-consent-impl').hidden = visible;
+    },
   };
 });

chrome/browser/ui/webui/chromeos/login/sync_consent_screen_handler.cc

@@ -85,6 +85,10 @@ void SyncConsentScreenHandler::Show() {
 
 void SyncConsentScreenHandler::Hide() {}
 
+void SyncConsentScreenHandler::SetThrobberVisible(bool visible) {
+  CallJS("setThrobberVisible", visible);
+}
+
 void SyncConsentScreenHandler::Initialize() {}
 
 void SyncConsentScreenHandler::GetAdditionalParameters(

chrome/browser/ui/webui/chromeos/login/sync_consent_screen_handler.h

@@ -28,6 +28,7 @@ class SyncConsentScreenHandler : public BaseScreenHandler,
   void Bind(SyncConsentScreen* screen) override;
   void Show() override;
   void Hide() override;
+  void SetThrobberVisible(bool visible) override;
 
  private:
   // BaseScreenHandler: