GitLab

ResourceDownloader uses BrowserThread::UI to post tasks to the delegate.
This introduces dependency on content/
Let delegate pass a TaskRunner to ResourceDownloader solves the issue.

BUG=803135

Change-Id: I44ebce8c72d65f99f90009ac9ca20709300cb2cd
Reviewed-on: https://chromium-review.googlesource.com/961528Reviewed-by: Xing Liu <xingliu@chromium.org>
Reviewed-by: David Trainor <dtrainor@chromium.org>
Commit-Queue: Min Qin <qinmin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543131}