Animated scroll shouldn't require main-frame for OOPIFs.

ui/compositor/compositor.cc

 // Copyright (c) 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 "ui/compositor/compositor.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <deque>
@@ skipping 235 matching lines @@
   if (context_factory_private_) {
     auto* manager = context_factory_private_->GetSurfaceManager();
     for (auto& client : child_frame_sinks_) {
       DCHECK(client.is_valid());
       manager->UnregisterFrameSinkHierarchy(frame_sink_id_, client);
     }
     manager->InvalidateFrameSinkId(frame_sink_id_);
   }
 }
 
+bool Compositor::IsForSubframe() {
+  return false;
+}
+
 void Compositor::AddFrameSink(const cc::FrameSinkId& frame_sink_id) {
   if (!context_factory_private_)
     return;
   context_factory_private_->GetSurfaceManager()->RegisterFrameSinkHierarchy(
       frame_sink_id_, frame_sink_id);
   child_frame_sinks_.insert(frame_sink_id);
 }
 
 void Compositor::RemoveFrameSink(const cc::FrameSinkId& frame_sink_id) {
   if (!context_factory_private_)
@@ skipping 331 matching lines @@
 void Compositor::TimeoutLocks() {
   // Make a copy, we're going to cause |active_locks_| to become
   // empty.
   std::vector<CompositorLock*> locks = active_locks_;
   for (auto* lock : locks)
     lock->TimeoutLock();
   DCHECK(active_locks_.empty());
 }
 
 }  // namespace ui