Make IsSolidColor() a property on CC scrollbar layers.

cc/trees/layer_tree_host_unittest_context.cc

Index: cc/trees/layer_tree_host_unittest_context.cc
diff --git a/cc/trees/layer_tree_host_unittest_context.cc b/cc/trees/layer_tree_host_unittest_context.cc
index f2349968947ab23fd76005e1da63941b5724c830..1a29cbaf1afe9104f42413b3cf8d1f3636568f32 100644
--- a/cc/trees/layer_tree_host_unittest_context.cc
+++ b/cc/trees/layer_tree_host_unittest_context.cc
@@ -1175,8 +1175,7 @@ class LayerTreeHostContextTestDontUseLostResources
     layer_tree_host()->SetDebugState(debug_state);
 
     scoped_refptr<ScrollbarLayer> scrollbar_ = ScrollbarLayer::Create(
-        scoped_ptr<Scrollbar>(new FakeScrollbar).Pass(),
-        content_->id());
+        scoped_ptr<Scrollbar>(new FakeScrollbar).Pass(), content_->id(), false);
     scrollbar_->SetBounds(gfx::Size(10, 10));
     scrollbar_->SetAnchorPoint(gfx::PointF());
     scrollbar_->SetIsDrawable(true);
@@ -1481,7 +1480,7 @@ class ScrollbarLayerLostContext : public LayerTreeHostContextTest {
   virtual void BeginTest() OVERRIDE {
     scoped_refptr<Layer> scroll_layer = Layer::Create();
     scrollbar_layer_ = FakeScrollbarLayer::Create(
-        false, true, scroll_layer->id());
+        false, true, scroll_layer->id(), false);
     scrollbar_layer_->SetBounds(gfx::Size(10, 100));
     layer_tree_host()->root_layer()->AddChild(scrollbar_layer_);
     layer_tree_host()->root_layer()->AddChild(scroll_layer);