[iOS][web] Fix context mime type for redirect

Instead of setting the Mime type in decidePolicyForNavigationResponse,
set it in didCommitNavigation. This is because the URL passed in the
navigation response might not be the same as the pending one.

Bug: 936750
Change-Id: I9b1dfcc78e1c5ab9265b2cec653c502e5d012d18
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1503432
Reviewed-by: Eugene But <eugenebut@chromium.org>
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638079}
1 file changed