Display local signin error without browser and record the path of selected profile in user manager.

chrome/browser/ui/webui/signin/user_manager_screen_handler.cc

Index: chrome/browser/ui/webui/signin/user_manager_screen_handler.cc
diff --git a/chrome/browser/ui/webui/signin/user_manager_screen_handler.cc b/chrome/browser/ui/webui/signin/user_manager_screen_handler.cc
index a56bbe86f0f4b62d786d9c086bb32c4b41c3cbb3..f19545ff63e063240d2e745226b25dcf113e0ab6 100644
--- a/chrome/browser/ui/webui/signin/user_manager_screen_handler.cc
+++ b/chrome/browser/ui/webui/signin/user_manager_screen_handler.cc
@@ -469,12 +469,24 @@ void UserManagerScreenHandler::HandleAuthenticatedLaunchUser(
     }
   }
 
-  // In order to support the upgrade case where we have a local hash but no
-  // password token, the user perform a full online reauth.
-  UserManager::ShowReauthDialog(web_ui()->GetWebContents()->GetBrowserContext(),
-                                email_address_,
-                                signin_metrics::Reason::REASON_UNLOCK);
+  content::BrowserContext* browser_context =
+      web_ui()->GetWebContents()->GetBrowserContext();
+
+#if !defined(OS_MACOSX)

[tommycli, 2016/09/21 18:26:59]

Why the mac vs. non-mac distinction?

Also the non-mac version lost the comment. Maybe the comment should be at the
top level.

[zmin, 2016/09/21 21:21:37]

Because the user_manager implementation on Mac is different but I don't have 
Mac for now. All Mac related condition will be removed in a separated CL once
the Mac part is finished. Since this one is big enough.

[tommycli, 2016/09/21 21:26:16]

Okay that's fine, please add a TODO for yourself explaining that.

[zmin, 2016/09/21 21:52:05]

Done.

+  if (!email_address_.empty()) {
+    // In order to support the upgrade case where we have a local hash but no
+    // password token, the user perform a full online reauth.
+    UserManager::ShowReauthDialog(browser_context, email_address_,
+                                  signin_metrics::Reason::REASON_UNLOCK);
+  } else {
+    // Fresh sign in via user manager without existed email address.
+    UserManager::ShowSigninDialog(browser_context, profile_path);
+  }
 }
+#else
+  UserManager::ShowReauthDialog(browser_context, email_address_,
+                                signin_metrics::Reason::REASON_UNLOCK);
+#endif
 
 void UserManagerScreenHandler::HandleRemoveUser(const base::ListValue* args) {
   DCHECK(args);