Update comment in arc_notification_content_view.

b/35786193 has been fixed, but the feature has not been turned on.
Update comment to reflect the state of this.

Bug: None (cleanup)
Test: manual.
Change-Id: Ie1e06f7a87ec3d1a8ef5e0113bcf19a01d95f02e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2505400
Auto-Submit: Sara Kato <sarakato@chromium.org>
Commit-Queue: Yuichiro Hanada <yhanada@chromium.org>
Reviewed-by: Yuichiro Hanada <yhanada@chromium.org>
Reviewed-by: Eliot Courtney <edcourtney@chromium.org>
Cr-Commit-Position: refs/heads/master@{#822125}

ash/public/cpp/external_arc/message_center/arc_notification_content_view.cc

@@ -687,10 +687,11 @@ void ArcNotificationContentView::OnPaint(gfx::Canvas* canvas) {
         item_->GetSnapshot().height(), contents_bounds.x(), contents_bounds.y(),
         contents_bounds.width(), contents_bounds.height(), true /* filter */);
   } else {
-    // Draw a blank background otherwise. The height of the view and surface are
-    // not exactly synced and user may see the blank area out of the surface.
-    // This code prevetns an ugly blank area and show white color instead.
-    // This should be removed after b/35786193 is done.
+    // Draw a white background otherwise. The height of the view/ surface and
+    // animation buffer size are not exactly synced and user may see the blank
+    // area out of the surface.
+    // TODO: This can be removed once both ARC and Chrome notifications have
+    // smooth expansion animations.
     canvas->DrawColor(SK_ColorWHITE);
   }
 }