Make IsSolidColor() a property on CC scrollbar layers.

cc/trees/layer_tree_host_impl_unittest.cc

Index: cc/trees/layer_tree_host_impl_unittest.cc
diff --git a/cc/trees/layer_tree_host_impl_unittest.cc b/cc/trees/layer_tree_host_impl_unittest.cc
index 7b1c59e92b3b69f8b363e0fd1ddc8e827d381236..9fe8bc69431884f2cdac555c1b237cd9513898ed 100644
--- a/cc/trees/layer_tree_host_impl_unittest.cc
+++ b/cc/trees/layer_tree_host_impl_unittest.cc
@@ -79,7 +79,7 @@ class LayerTreeHostImplTest : public testing::Test,
     LayerTreeSettings settings;
     settings.minimum_occlusion_tracking_size = gfx::Size();
     settings.impl_side_painting = true;
-    settings.solid_color_scrollbars = true;
+    settings.force_solid_color_scrollbars = true;
 
     host_impl_ = LayerTreeHostImpl::Create(settings,
                                            this,
@@ -690,7 +690,8 @@ TEST_F(LayerTreeHostImplTest, ScrollVerticallyByPageReturnsCorrectValue) {
       cc::ScrollbarLayerImpl::Create(
           host_impl_->active_tree(),
           20,
-          VERTICAL));
+          VERTICAL,
+          false));
   vertical_scrollbar->SetBounds(gfx::Size(15, 1000));
   host_impl_->RootScrollLayer()->SetVerticalScrollbarLayer(
       vertical_scrollbar.get());
@@ -1053,7 +1054,8 @@ TEST_F(LayerTreeHostImplTest, ScrollbarLinearFadeScheduling) {
   scoped_ptr<ScrollbarLayerImpl> scrollbar = ScrollbarLayerImpl::Create(
       host_impl_->active_tree(),
       4,
-      VERTICAL);
+      VERTICAL,
+      false);
   scroll->SetVerticalScrollbarLayer(scrollbar.get());
 
   scroll->AddChild(contents.Pass());