Update from https://crrev.com/320931

cc/base/swap_promise_monitor.cc

Index: cc/base/swap_promise_monitor.cc
diff --git a/cc/base/swap_promise_monitor.cc b/cc/base/swap_promise_monitor.cc
deleted file mode 100644
index 0c04f35ebc4be7cd9076e011aa88655904ff8dcc..0000000000000000000000000000000000000000
--- a/cc/base/swap_promise_monitor.cc
+++ /dev/null
@@ -1,31 +0,0 @@
-// Copyright 2013 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 "base/logging.h"
-#include "cc/base/swap_promise_monitor.h"
-#include "cc/trees/layer_tree_host.h"
-#include "cc/trees/layer_tree_host_impl.h"
-
-namespace cc {
-
-SwapPromiseMonitor::SwapPromiseMonitor(LayerTreeHost* layer_tree_host,
-                                       LayerTreeHostImpl* layer_tree_host_impl)
-    : layer_tree_host_(layer_tree_host),
-      layer_tree_host_impl_(layer_tree_host_impl) {
-  DCHECK((layer_tree_host && !layer_tree_host_impl) ||
-         (!layer_tree_host && layer_tree_host_impl));
-  if (layer_tree_host_)
-    layer_tree_host_->InsertSwapPromiseMonitor(this);
-  if (layer_tree_host_impl_)
-    layer_tree_host_impl_->InsertSwapPromiseMonitor(this);
-}
-
-SwapPromiseMonitor::~SwapPromiseMonitor() {
-  if (layer_tree_host_)
-    layer_tree_host_->RemoveSwapPromiseMonitor(this);
-  if (layer_tree_host_impl_)
-    layer_tree_host_impl_->RemoveSwapPromiseMonitor(this);
-}
-
-}  // namespace cc