Make IsSolidColor() a property on CC scrollbar layers.

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 ca7a37fa8b1baaa635a00c27b21c0da51a008480..c4f1fd1c7b0263f1bf93dbae20e4ec0865883198 100644
--- a/content/renderer/gpu/render_widget_compositor.cc
+++ b/content/renderer/gpu/render_widget_compositor.cc
@@ -271,12 +271,18 @@ scoped_ptr<RenderWidgetCompositor> RenderWidgetCompositor::Create(
   settings.can_use_lcd_text = false;
   settings.max_partial_texture_updates = 0;
   settings.use_linear_fade_scrollbar_animator = true;
-  settings.solid_color_scrollbars = true;
-  settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
-  settings.solid_color_scrollbar_thickness_dip = 3;
   settings.highp_threshold_min = 2048;
 #endif
 
+  if (cmd->HasSwitch(cc::switches::kForceSolidColorScrollbars) ) {
+    settings.force_solid_color_scrollbars = true;
+    settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
+    settings.solid_color_scrollbar_thickness_dip = 3;
+  } else if (settings.use_pinch_virtual_viewport) {

[aelias_OOO_until_Jul13, 2013/06/28 17:31:59]

I don't think these conditionals make a lot of sense, they are overly specific
to the current needs.  (For example, Android will eventually turn on
settings.use_pinch_virtual_viewport).

How about adding two more flags, one --solid-color-scrollbar-color=(whatever
color encoding makes sense) and --solid-color-scrollbar-thickness=?  (I was
already planning to add a color flag to change it in AndroidWebView
configuration anyway.)

+    settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
+    settings.solid_color_scrollbar_thickness_dip = 10;
+  }
+
   if (!compositor->initialize(settings))
     return scoped_ptr<RenderWidgetCompositor>();