refactor: take a uint8_t span in ValidateIntegrityOrDie() (#43613)

refactor: take a uint8_t span in ValidateIntegrityOrDie()

Doing some groundwork for fixing unsafe base::File() APIs:

- Change ValidateIntegrityOrDie() to take a span<const uint8_t> arg.
  We'll need this to migrate asar's base::File API calls away from the
  ones tagged `UNSAFE_BUFFER_USAGE` because the safe counterparts use
  span<uint8_t> too.

- Simplify ValidateIntegrityOrDie()'s implementation by using
  crypto::SHA256Hash() instead of reinventing the wheel.

Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: Charles Kerr <charles@charleskerr.com>

shell/common/asar/scoped_temporary_file.cc

@@ -68,9 +68,8 @@ bool ScopedTemporaryFile::InitFromFile(
   if (len != static_cast<int>(size))
     return false;
 
-  if (integrity.has_value()) {
-    ValidateIntegrityOrDie(buf.data(), buf.size(), integrity.value());
-  }
+  if (integrity)
+    ValidateIntegrityOrDie(base::as_byte_span(buf), *integrity);
 
   base::File dest(path_, base::File::FLAG_OPEN | base::File::FLAG_WRITE);
   if (!dest.IsValid())