[not for review - epic CL] Adding Elastic+Momentum+Layered scrolling to views::ScrollView

cc/trees/layer_tree_host_in_process.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_in_process.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 832 matching lines @@
       info->elastic_overscroll_delta.IsZero() && !info->top_controls_delta)
     return;
 
   // Preemptively apply the scroll offset and scale delta here before sending
   // it to the client.  If the client comes back and sets it to the same
   // value, then the layer can early out without needing a full commit.
   if (layer_tree_->inner_viewport_scroll_layer()) {
     layer_tree_->inner_viewport_scroll_layer()->SetScrollOffsetFromImplSide(
         gfx::ScrollOffsetWithDelta(
             layer_tree_->inner_viewport_scroll_layer()->scroll_offset(),
-            inner_viewport_scroll_delta));
+            inner_viewport_scroll_delta),
+        nullptr);
   }
 
   ApplyPageScaleDeltaFromImplSide(info->page_scale_delta);
   layer_tree_->SetElasticOverscrollFromImplSide(
       layer_tree_->elastic_overscroll() + info->elastic_overscroll_delta);
   // TODO(ccameron): pass the elastic overscroll here so that input events
   // may be translated appropriately.
   client_->ApplyViewportDeltas(inner_viewport_scroll_delta, gfx::Vector2dF(),
                                info->elastic_overscroll_delta,
                                info->page_scale_delta,
                                info->top_controls_delta);
   SetNeedsUpdateLayers();
 }
 
 void LayerTreeHostInProcess::ApplyScrollAndScale(ScrollAndScaleSet* info) {
   for (auto& swap_promise : info->swap_promises) {
     TRACE_EVENT_WITH_FLOW1("input,benchmark", "LatencyInfo.Flow",
                            TRACE_ID_DONT_MANGLE(swap_promise->TraceId()),
                            TRACE_EVENT_FLAG_FLOW_IN | TRACE_EVENT_FLAG_FLOW_OUT,
                            "step", "Main thread scroll update");
     swap_promise_manager_.QueueSwapPromise(std::move(swap_promise));
   }
 
   if (layer_tree_->root_layer()) {
     for (size_t i = 0; i < info->scrolls.size(); ++i) {
       Layer* layer = layer_tree_->LayerById(info->scrolls[i].layer_id);
       if (!layer)
         continue;
-      layer->SetScrollOffsetFromImplSide(gfx::ScrollOffsetWithDelta(
-          layer->scroll_offset(), info->scrolls[i].scroll_delta));
+      layer->SetScrollOffsetFromImplSide(
+          gfx::ScrollOffsetWithDelta(layer->scroll_offset(),
+                                     info->scrolls[i].scroll_delta),
+          &info->elastic_overscroll_delta);
       SetNeedsUpdateLayers();
     }
   }
 
   // This needs to happen after scroll deltas have been sent to prevent top
   // controls from clamping the layout viewport both on the compositor and
   // on the main thread.
   ApplyViewportDeltas(info);
 }
 
@@ skipping 144 matching lines @@
 
   debug_state_.FromProtobuf(proto.debug_state());
   has_gpu_rasterization_trigger_ = proto.has_gpu_rasterization_trigger();
   content_is_suitable_for_gpu_rasterization_ =
       proto.content_is_suitable_for_gpu_rasterization();
   id_ = proto.id();
   next_commit_forces_redraw_ = proto.next_commit_forces_redraw();
 }
 
 }  // namespace cc