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

ui/views/controls/md_slider.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/views/controls/md_slider.h"
 
 #include "third_party/skia/include/core/SkColor.h"
 #include "third_party/skia/include/core/SkPaint.h"
 #include "ui/gfx/animation/slide_animation.h"
 #include "ui/gfx/canvas.h"
@@ skipping 55 matching lines @@
       gfx::Rect(content.x(), y, full + extra_padding, kLineThickness),
       kSliderRoundedRadius, slider_paint);
   slider_paint.setColor(kDisabledColor);
   canvas->DrawRoundRect(gfx::Rect(x + kThumbRadius - extra_padding, y,
                                   empty + extra_padding, kLineThickness),
                         kSliderRoundedRadius, slider_paint);
 
   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.
   SkPaint paint;
   paint.setColor(current_thumb_color);
   paint.setFlags(SkPaint::kAntiAlias_Flag);
 
   if (!is_active_) {
     paint.setStrokeWidth(kThumbStroke);
     paint.setStyle(SkPaint::kStroke_Style);
@@ skipping 45 matching lines @@
     Slider::AnimationEnded(animation);
     return;
   }
   if (animation == highlight_animation_.get() &&
       !highlight_animation_->IsShowing()) {
     highlight_animation_.reset();
   }
 }
 
 }  // namespace views