Move UpgradeInsecureRequest to MixedContentChecker

This CL moves UpgradeInsecureRequest from FrameLoader to
MixedContentChecker as-is, and fixes its callers accordingly,
Because UpgradeInsecureRequest shouldn't be frame-specific.

Bug: 878274
Change-Id: Ia53589c52c8b49290f67426d89c4b09eef1d20c6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1580259
Reviewed-by: Kenichi Ishibashi <bashi@chromium.org>
Reviewed-by: Hiroki Nakagawa <nhiroki@chromium.org>
Commit-Queue: Hiroshige Hayashizaki <hiroshige@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653901}
6 files changed