cc: Disallow scroll offset animations when impl-scrolling isn't supported

cc/trees/single_thread_proxy.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/single_thread_proxy.h"
 
 #include "base/auto_reset.h"
 #include "base/debug/trace_event.h"
 #include "cc/debug/benchmark_instrumentation.h"
 #include "cc/output/context_provider.h"
@@ skipping 373 matching lines @@
 void SingleThreadProxy::ForceSerializeOnSwapBuffers() {
   {
     DebugScopedSetImplThread impl(this);
     if (layer_tree_host_impl_->renderer()) {
       DCHECK(!layer_tree_host_->output_surface_lost());
       layer_tree_host_impl_->renderer()->DoNoOp();
     }
   }
 }
 
+bool SingleThreadProxy::SupportsImplScrolling() const {
+  return false;
+}
+
 bool SingleThreadProxy::ShouldComposite() const {
   DCHECK(Proxy::IsImplThread());
   return layer_tree_host_impl_->visible() &&
          layer_tree_host_impl_->CanDraw();
 }
 
 void SingleThreadProxy::UpdateBackgroundAnimateTicking() {
   DCHECK(Proxy::IsImplThread());
   layer_tree_host_impl_->UpdateBackgroundAnimateTicking(
       !ShouldComposite() && layer_tree_host_impl_->active_tree()->root_layer());
@@ skipping 47 matching lines @@
 void SingleThreadProxy::DidSwapFrame() {
   if (next_frame_is_newly_committed_frame_) {
     next_frame_is_newly_committed_frame_ = false;
     layer_tree_host_->DidCommitAndDrawFrame();
   }
 }
 
 bool SingleThreadProxy::CommitPendingForTesting() { return false; }
 
 }  // namespace cc