The current integration tests for the Passwords Keyboard accessory mocks the native part of Chrome and basically skips the ManualFillingBridge.
It merely tests how the UI components (keyboard accessory, accessory sheet and password accessory sheet) integrate with another.

We should make provide a helper class that allows to set native data to check the C++ code as well.

This would prevent heavy regressions such as issue 907419 and increase our coverage significantly.