[CrOS PhoneHub] Fit all of the notification opt-in text.

The text was previously truncated in English. This CL ensures that
the entire string is visible in whatever language, taking as many
lines as it needs.

Screenshots:
https://screenshot.googleplex.com/36o7AGXKQ46TCAV
https://screenshot.googleplex.com/Af3XxC4vvt6TFsB

Fixed: 1148040
Bug: 1106937
Change-Id: Ibae0db5ab671c2514d17dca1d23ac90b6fca560d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2534690Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Commit-Queue: Regan Hsu <hsuregan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826816}

ash/system/phonehub/notification_opt_in_view.cc

@@ -117,6 +117,8 @@ void NotificationOptInView::InitLayout() {
                                .DeriveWithWeight(gfx::Font::Weight::MEDIUM));
   text_label_->SetLineHeight(kTextLabelLineHeightDip);
   text_label_->SetBorder(views::CreateEmptyBorder(kTextLabelBorderInsets));
+  text_label_->SetMultiLine(/*multi_line=*/true);
+  text_label_->SetHorizontalAlignment(gfx::HorizontalAlignment::ALIGN_LEFT);
   text_label_->SetText(l10n_util::GetStringFUTF16(
       IDS_ASH_PHONE_HUB_NOTIFICATION_OPT_IN_DESCRIPTION,
       ui::GetChromeOSDeviceName()));