Performance Toolkit 是一个chrome devtools插件，用来方便观察performance的数据。
Chrome App Store: https://chrome.google.com/webstore/detail/performance-toolkit/ddflmknikhhoiklhchkfpeiadchflbcg
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.