cc/blimp: Add a LayerTreeHostRemote implementation.

cc/trees/layer_tree_host.cc

+// Copyright 2016 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.h"
+
+#include "base/atomic_sequence_num.h"
+
+namespace cc {
+namespace {
+static base::StaticAtomicSequenceNumber s_layer_tree_host_sequence_number;
+}  // namespace
+
+// static
+int LayerTreeHost::GenerateHostId() {
+  return s_layer_tree_host_sequence_number.GetNext() + 1;
+}
+
+}  // namespace cc