Remove ResourceRequest::frame_type_

This is not used anymore, being always kNone. We clean up all
conditional logic based on the frame type, especially in
MixedContentChecker.

Bug: 855189
Change-Id: I2ed91e1969ac45de09c930281e4485093a70d822
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1515691
Commit-Queue: Dmitry Gozman <dgozman@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#642821}
27 files changed