GitLab

- Add metrics for ad injector install location.
- Add metrics for injected ad type.
- Ignore added elements that have a src of the current page.

BUG=357204

Review URL: https://codereview.chromium.org/292313006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@273066 0039d316-1c4b-4281-b951-d872f2087c98