Make scrollable viewport size no longer depend on clip layer.

cc/layers/scrollbar_layer_impl.cc

 // Copyright 2012 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 "cc/layers/scrollbar_layer_impl.h"
 
 #include "cc/animation/scrollbar_animation_controller.h"
 #include "cc/layers/layer.h"
 #include "cc/layers/quad_sink.h"
 #include "cc/quads/solid_color_draw_quad.h"
@@ skipping 23 matching lines @@
       current_pos_(0.f),
       maximum_(0),
       thumb_thickness_(0),
       thumb_length_(0),
       track_start_(0),
       track_length_(0),
       orientation_(orientation),
       vertical_adjust_(0.f),
       visible_to_total_length_ratio_(1.f),
       scroll_layer_id_(Layer::INVALID_ID),
-      is_scrollable_area_active_(false),
-      is_scroll_view_scrollbar_(false),
-      enabled_(false),
-      is_custom_scrollbar_(false),
       is_overlay_scrollbar_(false) {}
 
 ScrollbarLayerImpl::~ScrollbarLayerImpl() {}
 
 ScrollbarLayerImpl* ScrollbarLayerImpl::ToScrollbarLayer() {
   return this;
 }
 
 scoped_ptr<LayerImpl> ScrollbarLayerImpl::CreateLayerImpl(
     LayerTreeImpl* tree_impl) {
   return ScrollbarLayerImpl::Create(tree_impl,
                                     id(),
                                     orientation_).PassAs<LayerImpl>();
 }
 
 void ScrollbarLayerImpl::PushPropertiesTo(LayerImpl* layer) {
   LayerImpl::PushPropertiesTo(layer);
 
   ScrollbarLayerImpl* scrollbar_layer = static_cast<ScrollbarLayerImpl*>(layer);
 
   scrollbar_layer->set_thumb_thickness(thumb_thickness_);
   scrollbar_layer->set_thumb_length(thumb_length_);
   scrollbar_layer->set_track_start(track_start_);
   scrollbar_layer->set_track_length(track_length_);
+  scrollbar_layer->set_is_overlay_scrollbar(is_overlay_scrollbar_);
 
   scrollbar_layer->set_track_resource_id(track_resource_id_);
   scrollbar_layer->set_thumb_resource_id(thumb_resource_id_);
 }
 
 bool ScrollbarLayerImpl::WillDraw(DrawMode draw_mode,
                                   ResourceProvider* resource_provider) {
   if (draw_mode == DRAW_MODE_RESOURCELESS_SOFTWARE &&
       !layer_tree_impl()->settings().solid_color_scrollbars)
     return false;
@@ skipping 179 matching lines @@
 void ScrollbarLayerImpl::DidLoseOutputSurface() {
   track_resource_id_ = 0;
   thumb_resource_id_ = 0;
 }
 
 const char* ScrollbarLayerImpl::LayerTypeAsString() const {
   return "cc::ScrollbarLayerImpl";
 }
 
 }  // namespace cc