GMC: Ensure left-alignment of title and artist labels

This CL adds horizontal alignment to the title and artist labels to
ensure that they stay properly aligned to the left. This fixes a bug
where overflowing text would shift slightly to the right.

Bug: 1021589
Change-Id: I7c007f4d7af4abe1556941b901a57569dcc41f30
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1899089
Auto-Submit: Tommy Steimel <steimel@chromium.org>
Reviewed-by: Jazz Xu <jazzhsu@chromium.org>
Commit-Queue: Tommy Steimel <steimel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#712663}

components/media_message_center/media_notification_view.cc

@@ -157,12 +157,14 @@ MediaNotificationView::MediaNotificationView(
   title_label->SetFontList(base_font_list.Derive(
       0, gfx::Font::FontStyle::NORMAL, gfx::Font::Weight::MEDIUM));
   title_label->SetLineHeight(kTitleArtistLineHeight);
+  title_label->SetHorizontalAlignment(gfx::ALIGN_LEFT);
   title_label_ = title_artist_row_->AddChildView(std::move(title_label));
 
   auto artist_label = std::make_unique<views::Label>(
       base::string16(), views::style::CONTEXT_LABEL,
       views::style::STYLE_PRIMARY);
   artist_label->SetLineHeight(kTitleArtistLineHeight);
+  artist_label->SetHorizontalAlignment(gfx::ALIGN_LEFT);
   artist_label_ = title_artist_row_->AddChildView(std::move(artist_label));
 
   // |button_row_| contains the buttons for controlling playback.