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 enables these warnings and fixes the remaining known issues.)

Bug: chromium:1292951
PiperOrigin-RevId: 480981210
Change-Id: I92d5023c6833e24d6aa29b10d433116329972f41