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

cc/layers/scrollbar_layer.cc

Index: cc/layers/scrollbar_layer.cc
diff --git a/cc/layers/scrollbar_layer.cc b/cc/layers/scrollbar_layer.cc
index f2c46a82202a200833511ae8750b4f5b44a637e4..ace27f969c73b47a95bc4deae995973bfa71c6d0 100644
--- a/cc/layers/scrollbar_layer.cc
+++ b/cc/layers/scrollbar_layer.cc
@@ -34,8 +34,8 @@ scoped_refptr<ScrollbarLayer> ScrollbarLayer::Create(
 ScrollbarLayer::ScrollbarLayer(
     scoped_ptr<Scrollbar> scrollbar,
     int scroll_layer_id)
-    : scrollbar_(scrollbar.Pass()),
-      scroll_layer_id_(scroll_layer_id),
+    : ScrollbarLayerBase(scroll_layer_id, scrollbar->Orientation()),
+      scrollbar_(scrollbar.Pass()),
       texture_format_(GL_INVALID_ENUM) {
   if (!scrollbar_->IsOverlay())
     SetShouldScrollOnMainThread(true);
@@ -43,31 +43,26 @@ ScrollbarLayer::ScrollbarLayer(
 
 ScrollbarLayer::~ScrollbarLayer() {}
 
-void ScrollbarLayer::SetScrollLayerId(int id) {
-  if (id == scroll_layer_id_)
-    return;
-
-  scroll_layer_id_ = id;
-  SetNeedsFullTreeSync();
-}
-
 bool ScrollbarLayer::OpacityCanAnimateOnImplThread() const {
   return scrollbar_->IsOverlay();
 }
 
-ScrollbarOrientation ScrollbarLayer::Orientation() const {
-  return scrollbar_->Orientation();
-}
+ScrollbarLayerBase* ScrollbarLayer::ToScrollbarLayerBase() { return this; }
 
 int ScrollbarLayer::MaxTextureSize() {
   DCHECK(layer_tree_host());
   return layer_tree_host()->GetRendererCapabilities().max_texture_size;
 }
 
-float ScrollbarLayer::ClampScaleToMaxTextureSize(float scale) {
-  if (layer_tree_host()->settings().solid_color_scrollbars)
-    return scale;
+void ScrollbarLayer::SetScrollLayerId(int id) {
+  if (id == scroll_layer_id_)
+    return;
 
+  scroll_layer_id_ = id;
+  SetNeedsFullTreeSync();
+}
+
+float ScrollbarLayer::ClampScaleToMaxTextureSize(float 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.
@@ -104,21 +99,7 @@ void ScrollbarLayer::PushPropertiesTo(LayerImpl* layer) {
 
   ScrollbarLayerImpl* scrollbar_layer = static_cast<ScrollbarLayerImpl*>(layer);
 
-  if (layer_tree_host() &&
-      layer_tree_host()->settings().solid_color_scrollbars) {
-    int thickness_override =
-        layer_tree_host()->settings().solid_color_scrollbar_thickness_dip;
-    if (thickness_override != -1) {
-      scrollbar_layer->set_thumb_thickness(thickness_override);
-    } else {
-      if (Orientation() == HORIZONTAL)
-        scrollbar_layer->set_thumb_thickness(bounds().height());
-      else
-        scrollbar_layer->set_thumb_thickness(bounds().width());
-    }
-  } else {
-    scrollbar_layer->set_thumb_thickness(thumb_thickness_);
-  }
+  scrollbar_layer->set_thumb_thickness(thumb_thickness_);
   scrollbar_layer->set_thumb_length(thumb_length_);
   if (Orientation() == HORIZONTAL) {
     scrollbar_layer->set_track_start(track_rect_.x());
@@ -139,10 +120,6 @@ void ScrollbarLayer::PushPropertiesTo(LayerImpl* layer) {
     scrollbar_layer->set_thumb_resource_id(0);
 }
 
-ScrollbarLayer* ScrollbarLayer::ToScrollbarLayer() {
-  return this;
-}
-
 void ScrollbarLayer::SetLayerTreeHost(LayerTreeHost* host) {
   if (!host || host != layer_tree_host()) {
     track_updater_ = NULL;
@@ -174,9 +151,6 @@ class ScrollbarPartPainter : public LayerPainter {
 };
 
 void ScrollbarLayer::CreateUpdaterIfNeeded() {
-  if (layer_tree_host()->settings().solid_color_scrollbars)
-    return;
-
   texture_format_ =
       layer_tree_host()->GetRendererCapabilities().best_texture_format;
 
@@ -211,9 +185,6 @@ void ScrollbarLayer::UpdatePart(CachingBitmapContentLayerUpdater* painter,
                                 LayerUpdater::Resource* resource,
                                 gfx::Rect rect,
                                 ResourceUpdateQueue* queue) {
-  if (layer_tree_host()->settings().solid_color_scrollbars)
-    return;
-
   // Skip painting and uploading if there are no invalidations and
   // we already have valid texture data.
   if (resource->texture()->have_backing_texture() &&
@@ -265,9 +236,6 @@ gfx::Rect ScrollbarLayer::ScrollbarLayerRectToContentRect(
 
 void ScrollbarLayer::SetTexturePriorities(
     const PriorityCalculator& priority_calc) {
-  if (layer_tree_host()->settings().solid_color_scrollbars)
-    return;
-
   if (content_bounds().IsEmpty())
     return;
   DCHECK_LE(content_bounds().width(), MaxTextureSize());
@@ -293,9 +261,6 @@ void ScrollbarLayer::Update(ResourceUpdateQueue* queue,
                             const OcclusionTracker* occlusion) {
   track_rect_ = scrollbar_->TrackRect();
 
-  if (layer_tree_host()->settings().solid_color_scrollbars)
-    return;
-
   {
     base::AutoReset<bool> ignore_set_needs_commit(&ignore_set_needs_commit_,
                                                   true);