Make IsSolidColor() a property on CC scrollbar layers.

content/renderer/gpu/render_widget_compositor.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/gpu/render_widget_compositor.h"
 
 #include <limits>
 #include <string>
 
 #include "base/command_line.h"
@@ skipping 253 matching lines @@
   settings.strict_layer_property_change_checking =
       cmd->HasSwitch(cc::switches::kStrictLayerPropertyChangeChecking);
 
   settings.use_map_image = cmd->HasSwitch(cc::switches::kUseMapImage);
 
 #if defined(OS_ANDROID)
   // TODO(danakj): Move these to the android code.
   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>();
 
   return compositor.Pass();
 }
 
 RenderWidgetCompositor::RenderWidgetCompositor(RenderWidget* widget)
   : suppress_schedule_composite_(false),
     widget_(widget) {
 }
@@ skipping 269 matching lines @@
   return RenderThreadImpl::current()->OffscreenContextProviderForMainThread();
 }
 
 scoped_refptr<cc::ContextProvider>
 RenderWidgetCompositor::OffscreenContextProviderForCompositorThread() {
   return RenderThreadImpl::current()->
       OffscreenContextProviderForCompositorThread();
 }
 
 }  // namespace content