GitLab

https://codereview.chromium.org/718203005/

<webview> tag will not support declarative content script API anymore. Instead,
we would like to support dynamically add/remove content scripts,
which are similar to content scripts for Chrome Extension.

BUG=461052

Review URL: https://codereview.chromium.org/975133002

Cr-Commit-Position: refs/heads/master@{#318972}