//ui/gfx: remove more unsafe buffers (2/n)

For one of these files the warnings were resolved earlier in an edit
to their header file, so this change just removes the pragmas. For the
text elider unittests, this change:

* Switches from raw arrays to std::array for the lists of test cases
* Switches from indexed for loops to range for loops where appropriate
* Renames some types & variables to be consistent between test cases

Bug: 354829279
Change-Id: Ia3dac41aefae923c65c62e9968b0becf67c704c3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5824523
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Elly FJ <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1350191}