Introducing gpu::CommandBufferId as a distinct, IdType<...>-based type.

gpu/command_buffer/common/sync_token.cc

+// Copyright 2015 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 "gpu/command_buffer/common/sync_token.h"
+
+namespace gpu {
+
+SyncToken::SyncToken()
+    : verified_flush_(false),
+      namespace_id_(CommandBufferNamespace::INVALID),
+      extra_data_field_(0),
+      release_count_(0) {}
+
+SyncToken::SyncToken(CommandBufferNamespace namespace_id,
+                     int32_t extra_data_field,
+                     CommandBufferId command_buffer_id,
+                     uint64_t release_count)
+    : verified_flush_(false),
+      namespace_id_(namespace_id),
+      extra_data_field_(extra_data_field),
+      command_buffer_id_(command_buffer_id),
+      release_count_(release_count) {}
+
+}  // namespace gpu