Revert "Implement scroll handler latency tracking"

cc/trees/layer_tree_host.cc

Index: cc/trees/layer_tree_host.cc
diff --git a/cc/trees/layer_tree_host.cc b/cc/trees/layer_tree_host.cc
index 770c39535977b8be4c54ef1b192b677ac43044aa..900b0d9e6e28e8296715bd8cac8e4dc45fe0d879 100644
--- a/cc/trees/layer_tree_host.cc
+++ b/cc/trees/layer_tree_host.cc
@@ -1019,40 +1019,31 @@ void LayerTreeHost::PaintLayerContents(
   in_paint_layer_contents_ = false;
 }
 
-void LayerTreeHost::ApplyScrollAndScale(ScrollAndScaleSet* info) {
+void LayerTreeHost::ApplyScrollAndScale(const ScrollAndScaleSet& info) {
   if (!root_layer_.get())
     return;
 
-  ScopedPtrVector<SwapPromise>::iterator it = info->swap_promises.begin();
-  for (; it != info->swap_promises.end(); ++it) {
-    scoped_ptr<SwapPromise> swap_promise(info->swap_promises.take(it));
-    TRACE_EVENT_FLOW_STEP0("input",
-                           "LatencyInfo.Flow",
-                           TRACE_ID_DONT_MANGLE(swap_promise->TraceId()),
-                           "Main thread scroll update");
-    QueueSwapPromise(swap_promise.Pass());
-  }
-
   gfx::Vector2d inner_viewport_scroll_delta;
   gfx::Vector2d outer_viewport_scroll_delta;
 
-  for (size_t i = 0; i < info->scrolls.size(); ++i) {
-    Layer* layer = LayerTreeHostCommon::FindLayerInSubtree(
-        root_layer_.get(), info->scrolls[i].layer_id);
+  for (size_t i = 0; i < info.scrolls.size(); ++i) {
+    Layer* layer =
+        LayerTreeHostCommon::FindLayerInSubtree(root_layer_.get(),
+                                                info.scrolls[i].layer_id);
     if (!layer)
       continue;
     if (layer == outer_viewport_scroll_layer_.get()) {
-      outer_viewport_scroll_delta += info->scrolls[i].scroll_delta;
+      outer_viewport_scroll_delta += info.scrolls[i].scroll_delta;
     } else if (layer == inner_viewport_scroll_layer_.get()) {
-      inner_viewport_scroll_delta += info->scrolls[i].scroll_delta;
+      inner_viewport_scroll_delta += info.scrolls[i].scroll_delta;
     } else {
       layer->SetScrollOffsetFromImplSide(layer->scroll_offset() +
-                                         info->scrolls[i].scroll_delta);
+                                         info.scrolls[i].scroll_delta);
     }
   }
 
   if (!inner_viewport_scroll_delta.IsZero() ||
-      !outer_viewport_scroll_delta.IsZero() || info->page_scale_delta != 1.f) {
+      !outer_viewport_scroll_delta.IsZero() || info.page_scale_delta != 1.f) {
     // SetScrollOffsetFromImplSide above could have destroyed the tree,
     // so re-get this layer before doing anything to it.
 
@@ -1069,11 +1060,11 @@ void LayerTreeHost::ApplyScrollAndScale(ScrollAndScaleSet* info) {
           outer_viewport_scroll_layer_->scroll_offset() +
           outer_viewport_scroll_delta);
     }
-    ApplyPageScaleDeltaFromImplSide(info->page_scale_delta);
+    ApplyPageScaleDeltaFromImplSide(info.page_scale_delta);
 
     client_->ApplyScrollAndScale(
         inner_viewport_scroll_delta + outer_viewport_scroll_delta,
-        info->page_scale_delta);
+        info.page_scale_delta);
   }
 }