CrOS GMC: Fix drop down icon layout bug.

This CL fix the drop down icon layout bug: the title view should not
take all the empty spaces.

Bug: 1133026
Change-Id: I1b6f85c84d03fd06bd219fef06ca49319d700408
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2442089
Auto-Submit: Jazz Xu <jazzhsu@chromium.org>
Reviewed-by: Tetsui Ohkubo <tetsui@chromium.org>
Commit-Queue: Tetsui Ohkubo <tetsui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813133}

ash/system/media/unified_media_controls_view.cc

@@ -195,7 +195,6 @@ UnifiedMediaControlsView::UnifiedMediaControlsView(
           AshColorProvider::ContentLayerType::kIconColorPrimary)));
   drop_down_icon_ = title_row->AddChildView(std::move(drop_down_icon));
 
-  title_row_layout->SetFlexForView(title_label_, 1);
   track_column->AddChildView(std::move(title_row));
 
   auto artist_label = std::make_unique<views::Label>();