Hide pinch viewport scrollbars when near minimum scale.

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 2b645e804fa43698b09f1915b0465e7250d2bf5a..2912f1084a8aa2672936911bcb5ca2dd9fa7d9bb 100644
--- a/content/renderer/gpu/render_widget_compositor.cc
+++ b/content/renderer/gpu/render_widget_compositor.cc
@@ -401,6 +401,11 @@ void RenderWidgetCompositor::Initialize() {
   settings.scrollbar_fade_delay_ms = 500;
   settings.scrollbar_fade_resize_delay_ms = 500;
   settings.scrollbar_fade_duration_ms = 300;
+
+  // When pinching in, only show the pinch-viewport overlay scrollbars if the
+  // page scale is at least some threshold away from the minimum. i.e. don't
+  // show the pinch scrollbars when at minimum scale.
+  settings.scrollbar_show_scale_threshold = 1.05f;
 #endif
 
   if (cmd->HasSwitch(switches::kEnableLowResTiling))