Migrate GURL accessors to Get* variants in //content

See goo.gle/gurl-accessor-migration for details. From the doc:
These are not simple accessors since they perform string allocations.
Sometimes these strings can be big (MBs) and the current naming scheme
frequently leads to people accidentally calling these rather than the
cheap `*_piece` accessors which return `string_view`.

This CL was generated by scaping build failures.

Bug: 448174617
Change-Id: I731d47fd9581af8ddd5dd919d6d50142cd9ea3b6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7001364
Commit-Queue: Daniel Cheng <dcheng@chromium.org>
Owners-Override: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1523325}