Change Aura overlay scrollbars from solid color to painted scrollbars.

content/renderer/gpu/render_widget_compositor.cc

Index: content/renderer/gpu/render_widget_compositor.cc
diff --git a/content/renderer/gpu/render_widget_compositor.cc b/content/renderer/gpu/render_widget_compositor.cc
index f2cfe6df89089e1d84dbdbbf892b2d9b84fbdd2d..ec3845f631db74bc94f77147d1e49afd4d926f80 100644
--- a/content/renderer/gpu/render_widget_compositor.cc
+++ b/content/renderer/gpu/render_widget_compositor.cc
@@ -60,6 +60,7 @@
 #include "third_party/WebKit/public/web/WebSelection.h"
 #include "ui/gl/gl_switches.h"
 #include "ui/native_theme/native_theme_switches.h"
+#include "ui/native_theme/overlay_scrollbar_constants_aura.h"
 
 #if defined(OS_ANDROID)
 #include "base/android/build_info.h"
@@ -420,14 +421,22 @@ cc::LayerTreeSettings RenderWidgetCompositor::GenerateLayerTreeSettings(
 #if !defined(OS_MACOSX)
   if (ui::IsOverlayScrollbarEnabled()) {
     settings.scrollbar_animator = cc::LayerTreeSettings::THINNING;
-    settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
+    settings.scrollbar_fade_delay_ms = ui::kOverlayScrollbarFadeOutDelayMs;
+    settings.scrollbar_fade_resize_delay_ms =
+        ui::kOverlayScrollbarFadeOutDelayMs;
+    settings.scrollbar_fade_duration_ms =
+        ui::kOverlayScrollbarFadeOutDurationMs;
+    settings.scrollbar_thinning_duration_ms =
+        ui::kOverlayScrollbarThinningDurationMs;
   } else {
+    // TODO(bokan): This section is probably unneeded? We don't use scrollbar
+    // animations for non overlay scrollbars.
     settings.scrollbar_animator = cc::LayerTreeSettings::LINEAR_FADE;
     settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
+    settings.scrollbar_fade_delay_ms = 500;
+    settings.scrollbar_fade_resize_delay_ms = 500;
+    settings.scrollbar_fade_duration_ms = 300;
   }
-  settings.scrollbar_fade_delay_ms = 500;
-  settings.scrollbar_fade_resize_delay_ms = 500;
-  settings.scrollbar_fade_duration_ms = 300;
 #endif  // !defined(OS_MACOSX)
 
   // On desktop, if there's over 4GB of memory on the machine, increase the