Use HTML messages to inform GAIA about deviceId.

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

Index: chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
diff --git a/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc b/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
index bffd9ef2b8a95f44bcb4a4519612dbcec09a2fde..e771305e5032b032e125a337ea12ef738bc55a4f 100644
--- a/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
+++ b/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
@@ -176,8 +176,10 @@ GaiaScreenHandler::GaiaScreenHandler(
       test_expects_complete_login_(false),
       use_easy_bootstrap_(false),
       signin_screen_handler_(NULL),
+      temporary_device_id_(base::GenerateGUID()),
       weak_factory_(this) {
   DCHECK(network_state_informer_.get());
+  DCHECK(!temporary_device_id_.empty());
 }
 
 GaiaScreenHandler::~GaiaScreenHandler() {
@@ -416,6 +418,7 @@ void GaiaScreenHandler::RegisterMessages() {
               &GaiaScreenHandler::HandleToggleWebviewSignin);
   AddCallback("toggleEasyBootstrap",
               &GaiaScreenHandler::HandleToggleEasyBootstrap);
+  AddCallback("attemptLogin", &GaiaScreenHandler::HandleAttemptLogin);
 }
 
 void GaiaScreenHandler::HandleFrameLoadingCompleted(int status) {
@@ -578,6 +581,16 @@ void GaiaScreenHandler::HandleToggleEasyBootstrap() {
   LoadAuthExtension(kForceReload, kSilentLoad, kNoOfflineUI);
 }
 
+void GaiaScreenHandler::HandleAttemptLogin(const std::string& email) {
+  std::string device_id =
+      user_manager::UserManager::Get()->GetKnownUserDeviceId(email);
+  if (!device_id.empty() && StartupUtils::IsWebviewSigninEnabled()) {
+    base::DictionaryValue params;
+    params.SetString("deviceId", device_id);
+    CallJS("updateDeviceId", params);
+  }
+}
+
 void GaiaScreenHandler::HandleGaiaUIReady() {
   if (focus_stolen_) {
     // Set focus to the Gaia page.
@@ -920,9 +933,13 @@ void GaiaScreenHandler::LoadAuthExtension(bool force,
     context.has_users = !Delegate()->GetUsers().empty();
   }
 
+  if (!context.email.empty()) {
+    context.device_id =
+        user_manager::UserManager::Get()->GetKnownUserDeviceId(context.email);
+  }
+
   if (context.device_id.empty()) {
-    context.device_id = base::GenerateGUID();
-    DCHECK(!context.device_id.empty());
+    context.device_id = temporary_device_id_;
   }
   context.session_is_ephemeral =
       ChromeUserManager::Get()->AreEphemeralUsersEnabled();