Rename one of two kThumbStroke in ui widget controls

Both the scrollbar and slider code have a kThumbStroke and
they are not the same. In jumbo builds those clash so this
patch renames the slider version to kSliderThumbStroke.

Bug: 773275
Change-Id: I53f7720bc34a3d71c9a0bb7061e0d185e1c8e68c
Reviewed-on: https://chromium-review.googlesource.com/786235
Reviewed-by: Michael Wasserman <msw@chromium.org>
Commit-Queue: Daniel Bratell <bratell@opera.com>
Cr-Commit-Position: refs/heads/master@{#518743}
diff --git a/ui/views/controls/slider.cc b/ui/views/controls/slider.cc
index 8af93e6..7859cca 100644
--- a/ui/views/controls/slider.cc
+++ b/ui/views/controls/slider.cc
@@ -56,7 +56,7 @@
 constexpr float kThumbHighlightRadius = 10.f;
 
 // The stroke of the thumb when the slider is disabled.
-constexpr int kThumbStroke = 2;
+constexpr int kSliderThumbStroke = 2;
 
 // Duration of the thumb highlight growing effect animation.
 constexpr int kSlideHighlightChangeDurationMs = 150;
@@ -299,12 +299,13 @@
   flags.setAntiAlias(true);
 
   if (!is_active_) {
-    flags.setStrokeWidth(kThumbStroke);
+    flags.setStrokeWidth(kSliderThumbStroke);
     flags.setStyle(cc::PaintFlags::kStroke_Style);
   }
   canvas->DrawCircle(
       thumb_center,
-      is_active_ ? kThumbRadius : (kThumbRadius - kThumbStroke / 2), flags);
+      is_active_ ? kThumbRadius : (kThumbRadius - kSliderThumbStroke / 2),
+      flags);
 }
 
 void Slider::OnFocus() {