GitLab

This CL adds displaying live log from the request manager of the selected
file system.

TEST=Tested manually with a testing extension.
BUG=376095

Review URL: https://codereview.chromium.org/301873002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@274436 0039d316-1c4b-4281-b951-d872f2087c98