change from using chrome_gen to chrome

Move to using the `package:chrome` library from `package:chrome_gen`. All the content of chrome_gen has been moved into chrome; `chrome_gen` is now deprecated and `chrome` is the new system-of-record, where bug-fixing will occur and new features will show up.

https://github.com/dart-gde/chrome.dart

@dinhviethoa for review

@financeCoding for FYI