Refactor cc scrollbar layers to separate solid-color vs desktop.

cc/layers/painted_scrollbar_layer.cc

Index: cc/layers/painted_scrollbar_layer.cc
diff --git a/cc/layers/painted_scrollbar_layer.cc b/cc/layers/painted_scrollbar_layer.cc
index f2c3e450bd89177d9f62e45b267a161173a4badd..82b2858c31ae7cf732d2e6a4f8a32c0d8192c9c1 100644
--- a/cc/layers/painted_scrollbar_layer.cc
+++ b/cc/layers/painted_scrollbar_layer.cc
@@ -44,6 +44,10 @@ PaintedScrollbarLayer::PaintedScrollbarLayer(
 
 PaintedScrollbarLayer::~PaintedScrollbarLayer() {}
 
+int PaintedScrollbarLayer::ScrollLayerId() const {
+  return scroll_layer_id_;
+}
+
 void PaintedScrollbarLayer::SetScrollLayerId(int id) {
   if (id == scroll_layer_id_)
     return;
@@ -56,7 +60,7 @@ bool PaintedScrollbarLayer::OpacityCanAnimateOnImplThread() const {
   return scrollbar_->IsOverlay();
 }
 
-ScrollbarOrientation PaintedScrollbarLayer::Orientation() const {
+ScrollbarOrientation PaintedScrollbarLayer::orientation() const {
   return scrollbar_->Orientation();
 }
 
@@ -66,9 +70,6 @@ int PaintedScrollbarLayer::MaxTextureSize() {
 }
 
 float PaintedScrollbarLayer::ClampScaleToMaxTextureSize(float scale) {
-  if (layer_tree_host()->settings().solid_color_scrollbars)
-    return scale;
-
   // If the scaled content_bounds() is bigger than the max texture size of the
   // device, we need to clamp it by rescaling, since content_bounds() is used
   // below to set the texture size.
@@ -107,14 +108,9 @@ void PaintedScrollbarLayer::PushPropertiesTo(LayerImpl* layer) {
   PaintedScrollbarLayerImpl* scrollbar_layer =
       static_cast<PaintedScrollbarLayerImpl*>(layer);
 
-  if (layer_tree_host() &&
-      layer_tree_host()->settings().solid_color_scrollbars) {
-    scrollbar_layer->SetThumbThickness(scrollbar_->ThumbThickness());
-  } else {
-    scrollbar_layer->SetThumbThickness(thumb_thickness_);
-  }
+  scrollbar_layer->SetThumbThickness(thumb_thickness_);
   scrollbar_layer->SetThumbLength(thumb_length_);
-  if (Orientation() == HORIZONTAL) {
+  if (orientation() == HORIZONTAL) {
     scrollbar_layer->SetTrackStart(
         track_rect_.x() - scrollbar_->Location().x());
     scrollbar_layer->SetTrackLength(track_rect_.width());
@@ -135,7 +131,7 @@ void PaintedScrollbarLayer::PushPropertiesTo(LayerImpl* layer) {
   needs_push_properties_ = true;
 }
 
-PaintedScrollbarLayer* PaintedScrollbarLayer::ToScrollbarLayer() {
+ScrollbarLayerInterface* PaintedScrollbarLayer::ToScrollbarLayer() {
   return this;
 }
 
@@ -165,7 +161,7 @@ gfx::Rect PaintedScrollbarLayer::ScrollbarLayerRectToContentRect(
 
 gfx::Rect PaintedScrollbarLayer::OriginThumbRect() const {
   gfx::Size thumb_size;
-  if (Orientation() == HORIZONTAL) {
+  if (orientation() == HORIZONTAL) {
     thumb_size =
         gfx::Size(scrollbar_->ThumbLength(), scrollbar_->ThumbThickness());
   } else {
@@ -190,8 +186,7 @@ bool PaintedScrollbarLayer::Update(ResourceUpdateQueue* queue,
   gfx::Rect scaled_track_rect = ScrollbarLayerRectToContentRect(
       gfx::Rect(scrollbar_->Location(), bounds()));
 
-  if (layer_tree_host()->settings().solid_color_scrollbars ||
-      track_rect_.IsEmpty() || scaled_track_rect.IsEmpty())
+  if (track_rect_.IsEmpty() || scaled_track_rect.IsEmpty())
     return false;
 
   {
@@ -215,7 +210,6 @@ bool PaintedScrollbarLayer::Update(ResourceUpdateQueue* queue,
 scoped_refptr<UIResourceBitmap> PaintedScrollbarLayer::RasterizeScrollbarPart(
     gfx::Rect rect,
     ScrollbarPart part) {
-  DCHECK(!layer_tree_host()->settings().solid_color_scrollbars);
   DCHECK(!rect.size().IsEmpty());
 
   scoped_refptr<UIResourceBitmap> bitmap =