Chrome OS: Fix DCHECK in Offline Gaia screen.

Offline Gaia did not have dedicated API, so it crashed when trying to
sign-in as non-existing user. This CL adds a dedicated API which displays error
message to user.

Bug: 863847
Cq-Include-Trybots: luci.chromium.try:closure_compilation
Change-Id: I8354a88befb7cb99a64519c3f3d07449ead8fc4d
Reviewed-on: https://chromium-review.googlesource.com/1141654
Commit-Queue: Alexander Alekseev <alemate@chromium.org>
Reviewed-by: Roman Sorokin <rsorokin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576256}

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

@@ -1084,8 +1084,8 @@ login.createScreen('GaiaSigninScreen', 'gaia-signin', function() {
       } else if (credentials.useOffline) {
         this.email = credentials.email;
         chrome.send(
-            'authenticateUser',
-            [credentials.email, credentials.password, false]);
+            'completeOfflineAuthentication',
+            [credentials.email, credentials.password]);
       } else if (credentials.authCode) {
         chrome.send('completeAuthentication', [
           credentials.gaiaId, credentials.email, credentials.password,

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

@@ -41,6 +41,7 @@
 #include "chrome/browser/chromeos/lock_screen_apps/state_controller.h"
 #include "chrome/browser/chromeos/login/easy_unlock/easy_unlock_service.h"
 #include "chrome/browser/chromeos/login/error_screens_histogram_helper.h"
+#include "chrome/browser/chromeos/login/help_app_launcher.h"
 #include "chrome/browser/chromeos/login/hwid_checker.h"
 #include "chrome/browser/chromeos/login/lock/screen_locker.h"
 #include "chrome/browser/chromeos/login/lock/webui_screen_locker.h"
@@ -501,6 +502,8 @@ void SigninScreenHandler::DeclareLocalizedValues(
 
 void SigninScreenHandler::RegisterMessages() {
   AddCallback("authenticateUser", &SigninScreenHandler::HandleAuthenticateUser);
+  AddCallback("completeOfflineAuthentication",
+              &SigninScreenHandler::HandleCompleteOfflineAuthentication);
   AddCallback("launchIncognito", &SigninScreenHandler::HandleLaunchIncognito);
   AddCallback("showSupervisedUserCreationScreen",
               &SigninScreenHandler::HandleShowSupervisedUserCreationScreen);
@@ -1189,6 +1192,12 @@ void SigninScreenHandler::UpdateAddButtonStatus() {
 void SigninScreenHandler::HandleAuthenticateUser(const AccountId& account_id,
                                                  const std::string& password,
                                                  bool authenticated_by_pin) {
+  AuthenticateExistingUser(account_id, password, authenticated_by_pin);
+}
+
+void SigninScreenHandler::AuthenticateExistingUser(const AccountId& account_id,
+                                                   const std::string& password,
+                                                   bool authenticated_by_pin) {
   if (!delegate_)
     return;
   DCHECK_EQ(account_id.GetUserEmail(),
@@ -1199,7 +1208,7 @@ void SigninScreenHandler::HandleAuthenticateUser(const AccountId& account_id,
   DCHECK(user);
   UserContext user_context;
   if (!user) {
-    LOG(ERROR) << "HandleAuthenticateUser: User not found! account type="
+    LOG(ERROR) << "AuthenticateExistingUser: User not found! account type="
                << AccountId::AccountTypeToString(account_id.GetAccountType());
     const user_manager::UserType user_type =
         (account_id.GetAccountType() == AccountType::ACTIVE_DIRECTORY)
@@ -1226,6 +1235,28 @@ void SigninScreenHandler::HandleAuthenticateUser(const AccountId& account_id,
   UpdatePinKeyboardState(account_id);
 }
 
+void SigninScreenHandler::HandleCompleteOfflineAuthentication(
+    const std::string& email,
+    const std::string& password) {
+  const std::string sanitized_email = gaia::SanitizeEmail(email);
+  const AccountId account_id = user_manager::known_user::GetAccountId(
+      sanitized_email, std::string() /* id */, AccountType::UNKNOWN);
+  const user_manager::User* user =
+      user_manager::UserManager::Get()->FindUser(account_id);
+  if (!user) {
+    LOG(ERROR)
+        << "HandleCompleteOfflineAuthentication: User not found! account type="
+        << AccountId::AccountTypeToString(account_id.GetAccountType());
+    LoginDisplayHost::default_host()->GetLoginDisplay()->ShowError(
+        IDS_LOGIN_ERROR_OFFLINE_FAILED_NETWORK_NOT_CONNECTED, 1,
+        HelpAppLauncher::HELP_CANT_ACCESS_ACCOUNT);
+    return;
+  }
+
+  AuthenticateExistingUser(account_id, password,
+                           false /* authenticated_by_pin */);
+}
+
 void SigninScreenHandler::HandleLaunchIncognito() {
   UserContext context(user_manager::USER_TYPE_GUEST, EmptyAccountId());
   if (delegate_)

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

@@ -361,6 +361,8 @@ class SigninScreenHandler
   void HandleAuthenticateUser(const AccountId& account_id,
                               const std::string& password,
                               bool authenticated_by_pin);
+  void HandleCompleteOfflineAuthentication(const std::string& email,
+                                           const std::string& password);
   void HandleAttemptUnlock(const std::string& username);
   void HandleLaunchIncognito();
   void HandleLaunchPublicSession(const AccountId& account_id,
@@ -408,6 +410,11 @@ class SigninScreenHandler
   void HandleNewNoteLaunchAnimationDone();
   void HandleCloseLockScreenApp();
 
+  // Implements user sign-in.
+  void AuthenticateExistingUser(const AccountId& account_id,
+                                const std::string& password,
+                                bool authenticated_by_pin);
+
   // Sends the list of |keyboard_layouts| available for the |locale| that is
   // currently selected for the public session identified by |user_id|.
   void SendPublicSessionKeyboardLayouts(