Override IsRedirectResponse in extension protocols

The default URLFileRequestJob::IsRedirectResponse implementation is incorrect
for URLRequestExtensionJob (chrome-extension:-scheme) and ExtensionResourcesJob (chrome-extension-resource:-scheme).

BUG=388852,424961

Review URL: https://codereview.chromium.org/650453003

Cr-Commit-Position: refs/heads/master@{#300329}
(cherry picked from commit 54a4e4044b90ab88d59af098586cd82bc1cfac8e)

Review URL: https://codereview.chromium.org/690313002

Cr-Commit-Position: refs/branch-heads/2171@{#317}
Cr-Branched-From: 267aeeb8d85c8503a7fd12bd14654b8ea78d3974-refs/heads/master@{#297060}
2 files changed