Make all scrollable layers visible to hit testing.

cc/layers/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/layer_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 62 matching lines @@
       draw_blend_mode_(SkXfermode::kSrcOver_Mode),
       transform_tree_index_(TransformTree::kInvalidNodeId),
       effect_tree_index_(EffectTree::kInvalidNodeId),
       clip_tree_index_(ClipTree::kInvalidNodeId),
       scroll_tree_index_(ScrollTree::kInvalidNodeId),
       sorting_context_id_(0),
       current_draw_mode_(DRAW_MODE_NONE),
       mutable_properties_(MutableProperty::kNone),
       debug_info_(nullptr),
       has_preferred_raster_bounds_(false),
-      scrolls_drawn_descendant_(false),
       has_will_change_transform_hint_(false),
       needs_push_properties_(false),
       scrollbars_hidden_(false) {
   DCHECK_GT(layer_id_, 0);
 
   DCHECK(layer_tree_impl_);
   layer_tree_impl_->RegisterLayer(this);
   layer_tree_impl_->AddToElementMap(this);
 
   SetNeedsPushProperties();
@@ skipping 1006 matching lines @@
            .layer_transforms_should_scale_layer_contents) {
     return default_scale;
   }
 
   gfx::Vector2dF transform_scales = MathUtil::ComputeTransform2dScaleComponents(
       ScreenSpaceTransform(), default_scale);
   return std::max(transform_scales.x(), transform_scales.y());
 }
 
 }  // namespace cc