Store non-fast scrollable regions on ScrollNode

cc/trees/scroll_node.h

 // Copyright 2016 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.
 
 #ifndef CC_TREES_SCROLL_NODE_H_
 #define CC_TREES_SCROLL_NODE_H_
 
 #include "cc/base/cc_export.h"
+#include "cc/base/region.h"
 #include "cc/output/filter_operations.h"
 #include "ui/gfx/geometry/size.h"
 
 namespace base {
 namespace trace_event {
 class TracedValue;
 }  // namespace trace_event
 }  // namespace base
 
 namespace cc {
@@ skipping 11 matching lines @@
   // Unlike |id|, this id is stable across frames that don't change the
   // composited layer list.
   int owning_layer_id;
 
   // This is used for subtrees that should not be scrolled independently. For
   // example, when there is a layer that is not scrollable itself but is inside
   // a scrolling layer.
   bool scrollable;
 
   uint32_t main_thread_scrolling_reasons;
-  bool contains_non_fast_scrollable_region;
+
+  Region non_fast_scrollable_region;
 
   // Size of the clipped area, not including non-overlay scrollbars. Overlay
   // scrollbars do not affect the clipped area.
   gfx::Size scroll_clip_layer_bounds;
 
   // Bounds of the overflow scrolling area.
   gfx::Size bounds;
 
   bool max_scroll_offset_affected_by_page_scale;
   bool scrolls_inner_viewport;
   bool scrolls_outer_viewport;
 
   // This offset is used when |scrollable| is false and there isn't a transform
   // node already present that covers this offset.
   gfx::Vector2dF offset_to_transform_parent;
 
   bool should_flatten;
   bool user_scrollable_horizontal;
   bool user_scrollable_vertical;
   ElementId element_id;
   int transform_id;
 
   bool operator==(const ScrollNode& other) const;
   void AsValueInto(base::trace_event::TracedValue* value) const;
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_SCROLL_NODE_H_