Addresses failures with the following, in some files:
-Wshorten-64-to-32
-Wimplicit-int-conversion
-Wsign-compare
-Wsign-conversion
-Wtautological-unsigned-zero-compare

(This specific CL focuses on miscellaneous non-test source files.)

Bug: chromium:1292951
PiperOrigin-RevId: 473054605
Change-Id: Ifd7b24966613ca915511a3a607095508068200b8