Chromium change:
chromium/chromium@c7d760c
[Extensions] Add assert(extensions_enabled) in extensions BUILD.gns
There were two extensions BUILD.gn files that we couldn't
assert(extensions_enabled) in: extensions/BUILD.gn and
extensions/common/BUILD.gn. This was because of dependencies on
extensions that weren't properly guarded by
`#if BUILDFLAG(ENABLE_EXTENSIONS)`. Following recent CLs, we can now
fix this, and add the missing assertions to these two build files.
Bug: 731689
samartnik
1069fb2535