cros: Customize wrong password alert message in tablet mode

A small customization: in tablet mode, it doesn't make sense to display
a message related to a keyboard shortcut.

Bug: 887984
Change-Id: Ife9dbd11a0077b3c8001124b0224d50eac683b9c
Reviewed-on: https://chromium-review.googlesource.com/1242079Reviewed-by: Jacob Dufault <jdufault@chromium.org>
Commit-Queue: Wenzhao (Colin) Zang <wzang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594789}

ash/login/ui/lock_contents_view.cc

@@ -35,6 +35,7 @@
 #include "ash/system/status_area_widget.h"
 #include "ash/system/status_area_widget_delegate.h"
 #include "ash/system/tray/system_tray_notifier.h"
+#include "ash/wm/tablet_mode/tablet_mode_controller.h"
 #include "base/command_line.h"
 #include "base/strings/string16.h"
 #include "base/strings/utf_string_conversions.h"
@@ -212,6 +213,12 @@ bool IsPublicAccountUser(const mojom::LoginUserInfoPtr& user) {
   return user->basic_user_info->type == user_manager::USER_TYPE_PUBLIC_ACCOUNT;
 }
 
+bool IsTabletMode() {
+  return Shell::Get()
+      ->tablet_mode_controller()
+      ->IsTabletModeWindowManagerEnabled();
+}
+
 //
 // Computes a layout described as follows:
 //
@@ -1483,8 +1490,8 @@ void LockContentsView::ShowAuthErrorMessage() {
   base::Optional<int> bold_start;
   int bold_length = 0;
   // Display a hint to switch keyboards if there are other active input
-  // methods.
-  if (ime_controller->available_imes().size() > 1) {
+  // methods in clamshell mode.
+  if (ime_controller->available_imes().size() > 1 && !IsTabletMode()) {
     error_text += base::ASCIIToUTF16(" ");
     bold_start = error_text.length();
     base::string16 shortcut =