Get rid of net::LOAD_ENABLE_UPLOAD_PROGRESS.

It's only used by Loader code.

BUG=426442

Committed: https://crrev.com/69c091ddba1bddda795eb5da4e400d16b29cc732
Cr-Commit-Position: refs/heads/master@{#301110}

Review URL: https://codereview.chromium.org/669073003

Cr-Commit-Position: refs/heads/master@{#301843}
14 files changed