Focus password prompt only when AUTH_PASSWORD is added as AuthMethods.

Before this CL, |password_view_| is always focused when
HasAuthMethod(AUTH_PASSWORD) is true.

This CL limits the timing of focusing |password_view_| to only when
HasAuthMethod(AUTH_PASSWORD) is changed from false to true.

This CL also fixes a bug that users cannot focus inline reply using
virtual keyboard on the lock screen.

BUG=825781
TEST=manual

Change-Id: I7afa75af0b3c86bf0988d5cbd95edc192255785a
Reviewed-on: https://chromium-review.googlesource.com/980272Reviewed-by: Jacob Dufault <jdufault@chromium.org>
Reviewed-by: Tetsui Ohkubo <tetsui@chromium.org>
Reviewed-by: Yoshiki Iguchi <yoshiki@chromium.org>
Commit-Queue: Megumi Hattori <megumihattori@google.com>
Cr-Commit-Position: refs/heads/master@{#547402}

ash/login/ui/login_auth_user_view.cc

@@ -196,6 +196,8 @@ LoginAuthUserView::LoginAuthUserView(const mojom::LoginUserInfoPtr& user,
 LoginAuthUserView::~LoginAuthUserView() = default;
 
 void LoginAuthUserView::SetAuthMethods(uint32_t auth_methods) {
+  bool had_password = HasAuthMethod(AUTH_PASSWORD);
+
   auth_methods_ = static_cast<AuthMethods>(auth_methods);
   bool has_password = HasAuthMethod(AUTH_PASSWORD);
   bool has_pin = HasAuthMethod(AUTH_PIN);
@@ -205,7 +207,7 @@ void LoginAuthUserView::SetAuthMethods(uint32_t auth_methods) {
   password_view_->SetFocusEnabledForChildViews(has_password);
   password_view_->layer()->SetOpacity(has_password ? 1 : 0);
 
-  if (has_password)
+  if (!had_password && has_password)
     password_view_->RequestFocus();
 
   pin_view_->SetVisible(has_pin);