CrOS Shelf: Don't show nav background when in-app

Bug: 982512
Change-Id: Icedebc7c56989e5448f077251f3b6099f83e57ff
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1824357Reviewed-by: Andrew Xu <andrewxu@chromium.org>
Commit-Queue: Manu Cornet <manucornet@chromium.org>
Cr-Commit-Position: refs/heads/master@{#699570}

ash/shelf/shelf_navigation_widget.cc

@@ -247,9 +247,13 @@ void ShelfNavigationWidget::UpdateLayout() {
       tablet_mode ? GetSecondButtonBounds() : GetFirstButtonBounds());
   GetBackButton()->SetBoundsRect(GetFirstButtonBounds());
 
-  delegate_->SetBackground(views::CreateRoundedRectBackground(
-      ShelfConfig::Get()->shelf_control_permanent_highlight_background(),
-      ShelfConfig::Get()->control_border_radius()));
+  if (IsTabletMode() && ShelfConfig::Get()->is_in_app()) {
+    delegate_->SetBackground(views::CreateSolidBackground(SK_ColorTRANSPARENT));
+  } else {
+    delegate_->SetBackground(views::CreateRoundedRectBackground(
+        ShelfConfig::Get()->shelf_control_permanent_highlight_background(),
+        ShelfConfig::Get()->control_border_radius()));
+  }
 }
 
 }  // namespace ash