DevTools shows overlay scrollbar for enabled aura overlay scrollbar and mac

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 c3facc6e0d8d6bdf105365abcece22e90cfc6c74..7fcae59908115c34ec7c94ee6e886c8032234fd5 100644
--- a/content/renderer/gpu/render_widget_compositor.cc
+++ b/content/renderer/gpu/render_widget_compositor.cc
@@ -430,6 +430,13 @@ cc::LayerTreeSettings RenderWidgetCompositor::GenerateLayerTreeSettings(
         &settings.initial_debug_state.slow_down_raster_scale_factor);
   }
 
+  // This is default overlay scrollbar settings for DevTools mobile emulator.
+  // Android Overlay Scrollbar and Aura Overlay Scrollbar will override below.
+  settings.scrollbar_animator = cc::LayerTreeSettings::ANDROID_OVERLAY;
+  settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
+  settings.scrollbar_fade_delay = base::TimeDelta::FromMilliseconds(500);

[aelias_OOO_until_Jul13, 2017/05/09 19:20:23]

Please set this to 300 for consistency with Android.

[chaopeng, 2017/05/09 19:30:34]

Done.

+  settings.scrollbar_fade_duration = base::TimeDelta::FromMilliseconds(300);
+
 #if defined(OS_ANDROID)
   bool using_synchronous_compositor =
       GetContentClient()->UsingSynchronousCompositing();
@@ -447,7 +454,6 @@ cc::LayerTreeSettings RenderWidgetCompositor::GenerateLayerTreeSettings(
     settings.scrollbar_animator = cc::LayerTreeSettings::ANDROID_OVERLAY;
     settings.scrollbar_fade_delay = base::TimeDelta::FromMilliseconds(300);
     settings.scrollbar_fade_duration = base::TimeDelta::FromMilliseconds(300);
-    settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
   }
   settings.renderer_settings.highp_threshold_min = 2048;
   // Android WebView handles root layer flings itself.
@@ -494,13 +500,6 @@ cc::LayerTreeSettings RenderWidgetCompositor::GenerateLayerTreeSettings(
     settings.scrollbar_fade_duration = ui::kOverlayScrollbarFadeDuration;
     settings.scrollbar_thinning_duration =
         ui::kOverlayScrollbarThinningDuration;
-  } else {
-    // TODO(bokan): This section is probably unneeded? We don't use scrollbar
-    // animations for non overlay scrollbars.
-    settings.scrollbar_animator = cc::LayerTreeSettings::ANDROID_OVERLAY;
-    settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
-    settings.scrollbar_fade_delay = base::TimeDelta::FromMilliseconds(500);
-    settings.scrollbar_fade_duration = base::TimeDelta::FromMilliseconds(300);
   }
 #endif  // !defined(OS_MACOSX)