[TTS] Workaround for a seam in top_round overlay.

BUG=1008973

Change-Id: I796131daaa611a14647a5ea2d480dacfc43b2bfc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1836012
Commit-Queue: Donn Denman <donnd@chromium.org>
Commit-Queue: Matthew Jones <mdjones@chromium.org>
Auto-Submit: Donn Denman <donnd@chromium.org>
Reviewed-by: Matthew Jones <mdjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#702115}

chrome/browser/android/compositor/layer/overlay_panel_layer.cc

@@ -137,7 +137,8 @@ void OverlayPanelLayer::SetProperties(
         rounded_bar_top_resource->size().height() -
             rounded_bar_top_resource->padding().height());
 
-    const int vertical_fudge_factor = 1;  // gets rid of a seam.
+    // TODO(donnd): fix correctly.
+    const int vertical_fudge_factor = 2;  // Create an overlap to avoid a seam.
     rounded_top_adjust = rounded_bar_top_size.height() - vertical_fudge_factor;
 
     gfx::PointF rounded_bar_top_position(