[ash-md] Updates slider control to show thumb highlight when focused

Makes the thumb highlighted when the slider control is focused helping
when controlling volume or brightness with a keyboard.

BUG=658783

Review-Url: https://codereview.chromium.org/2619953002
Cr-Commit-Position: refs/heads/master@{#442816}

ash/common/system/tray/tray_popup_utils.cc

@@ -270,8 +270,6 @@ views::ToggleButton* TrayPopupUtils::CreateToggleButton(
       (kTrayToggleButtonWidth - toggle_size.width()) / 2;
   toggle->SetBorder(views::CreateEmptyBorder(
       gfx::Insets(vertical_padding, horizontal_padding)));
-  // TODO(varkha): remove this and implement toggle-button specific focus. See
-  // crbug.com/669124
   toggle->SetFocusPainter(CreateFocusPainter());
   toggle->SetAccessibleName(l10n_util::GetStringUTF16(accessible_name_id));
   return toggle;

ui/views/controls/md_slider.cc

@@ -73,12 +73,14 @@ void MdSlider::OnPaint(gfx::Canvas* canvas) {
   gfx::Point thumb_center(x, content.height() / 2);
 
   // Paint the thumb highlight if it exists.
-  if (is_active_ && thumb_highlight_radius_ > kThumbRadius) {
+  const int thumb_highlight_radius =
+      HasFocus() ? kThumbHighlightRadius : thumb_highlight_radius_;
+  if (is_active_ && thumb_highlight_radius > kThumbRadius) {
     SkPaint highlight;
     SkColor kHighlightColor = SkColorSetA(kActiveColor, kHighlightColorAlpha);
     highlight.setColor(kHighlightColor);
     highlight.setFlags(SkPaint::kAntiAlias_Flag);
-    canvas->DrawCircle(thumb_center, thumb_highlight_radius_, highlight);
+    canvas->DrawCircle(thumb_center, thumb_highlight_radius, highlight);
   }
 
   // Paint the thumb of the slider.