Animated scroll shouldn't consume unhandled scrolls for OOPIFs.

cc/trees/layer_tree_host_impl.cc

 // Copyright 2011 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/trees/layer_tree_host_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 3017 matching lines @@
       if (ScrollAnimationCreate(scroll_node, scroll_delta, delayed_by)) {
         scroll_animating_latched_node_id_ = scroll_node->id;
         return scroll_status;
       }
 
       pending_delta -= scroll_delta;
     }
   }
   scroll_state.set_is_ending(true);
   ScrollEnd(&scroll_state);
+  if (settings_.is_layer_tree_for_subframe &&
+      scroll_status.thread == SCROLL_ON_IMPL_THREAD) {
+    // If we get to here, we shouldn't return SCROLL_ON_IMPL_THREAD as otherwise
+    // we'll mark the scroll as handled and the scroll won't bubble.
+    scroll_status.thread = SCROLL_IGNORED;
+    scroll_status.main_thread_scrolling_reasons =
+        MainThreadScrollingReason::kNotScrollable;
+  }
   return scroll_status;
 }
 
 gfx::Vector2dF LayerTreeHostImpl::ScrollNodeWithViewportSpaceDelta(
     ScrollNode* scroll_node,
     const gfx::PointF& viewport_point,
     const gfx::Vector2dF& viewport_delta,
     ScrollTree* scroll_tree) {
   // Layers with non-invertible screen space transforms should not have passed
   // the scroll hit test in the first place.
@@ skipping 1251 matching lines @@
 }
 
 void LayerTreeHostImpl::UpdateScrollSourceInfo(bool is_wheel_scroll) {
   if (is_wheel_scroll)
     has_scrolled_by_wheel_ = true;
   else
     has_scrolled_by_touch_ = true;
 }
 
 }  // namespace cc