If the keyboard doesn't affect the size of the Chrome window, it will not be shown (see related issues [1]).

In order to show it, we have to figure out which signals are appropriate to detect it as the current system relies on the size of the Chrome Window changing. The existing InputMethodManagementWrapper seems to have done some work in this regard.

Furthermore, we have to figure out:
  - if we want to show it at all in these cases.
  - how the accessory sheet should be positioned/sized if it cannot replace the keyboard.
  - how it should look like (e.g. for floating and/or split keyboards).


[1] In case the keyboard is emulated or doesn't touch the Chrome window, the current detection cannot work. These issues are tracked here:
  Issue 902305 - Enable the keyboard accessory in VR
  Issue 874814 - Keyboard accessory for manual access to passwords is not shown in multi window mode(portrait)