Revert "Implement scroll handler latency tracking"

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index f3cf15627db99d0ecae826625f90b1887e425b1a..a2c8111e0e7329d569bb383dafb1b65c3b6cdfea 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -503,24 +503,6 @@ LayerTreeHostImpl::CreateLatencyInfoSwapPromiseMonitor(
       new LatencyInfoSwapPromiseMonitor(latency, NULL, this));
 }
 
-void LayerTreeHostImpl::QueueSwapPromiseForMainThreadScrollUpdate(
-    scoped_ptr<SwapPromise> swap_promise) {
-  if (swap_promises_for_main_thread_scroll_update_.size() >
-      kMaxQueuedSwapPromiseNumber) {
-    BreakSwapPromisesForMainThreadScrollUpdate(
-        SwapPromise::SWAP_PROMISE_LIST_OVERFLOW);
-  }
-  swap_promises_for_main_thread_scroll_update_.push_back(swap_promise.Pass());
-}
-
-void LayerTreeHostImpl::BreakSwapPromisesForMainThreadScrollUpdate(
-    SwapPromise::DidNotSwapReason reason) {
-  for (size_t i = 0; i < swap_promises_for_main_thread_scroll_update_.size();
-       i++)
-    swap_promises_for_main_thread_scroll_update_[i]->DidNotSwap(reason);
-  swap_promises_for_main_thread_scroll_update_.clear();
-}
-
 void LayerTreeHostImpl::TrackDamageForAllSurfaces(
     LayerImpl* root_draw_layer,
     const LayerImplList& render_surface_layer_list) {
@@ -2575,11 +2557,6 @@ bool LayerTreeHostImpl::ScrollBy(const gfx::Point& viewport_point,
 
   bool did_scroll_content = did_scroll_x || did_scroll_y;
   if (did_scroll_content) {
-    // If we are scrolling with an active scroll handler, forward latency
-    // tracking information to the main thread so the delay introduced by the
-    // handler is accounted for.
-    if (scroll_affects_scroll_handler())
-      NotifySwapPromiseMonitorsOfForwardingToMainThread();
     client_->SetNeedsCommitOnImplThread();
     SetNeedsRedraw();
     client_->RenewTreePriority();
@@ -2881,7 +2858,6 @@ scoped_ptr<ScrollAndScaleSet> LayerTreeHostImpl::ProcessScrollDeltas() {
   CollectScrollDeltas(scroll_info.get(), active_tree_->root_layer());
   scroll_info->page_scale_delta = active_tree_->page_scale_delta();
   active_tree_->set_sent_page_scale_delta(scroll_info->page_scale_delta);
-  scroll_info->swap_promises.swap(swap_promises_for_main_thread_scroll_update_);
 
   return scroll_info.Pass();
 }
@@ -3258,12 +3234,6 @@ void LayerTreeHostImpl::NotifySwapPromiseMonitorsOfSetNeedsRedraw() {
     (*it)->OnSetNeedsRedrawOnImpl();
 }
 
-void LayerTreeHostImpl::NotifySwapPromiseMonitorsOfForwardingToMainThread() {
-  std::set<SwapPromiseMonitor*>::iterator it = swap_promise_monitor_.begin();
-  for (; it != swap_promise_monitor_.end(); it++)
-    (*it)->OnForwardScrollUpdateToMainThreadOnImpl();
-}
-
 void LayerTreeHostImpl::RegisterPictureLayerImpl(PictureLayerImpl* layer) {
   DCHECK(std::find(picture_layers_.begin(), picture_layers_.end(), layer) ==
          picture_layers_.end());