Synthesizing keyboard events is dangerous and such API is requested only by
fuzzing test. So, we should add it into FuzzingFunctions which is built
only when |ac_add_options --enable-fuzzing| is specified and enabled by
the pref.
This patch implements the API as synthesizing keyboard events in the focused
widget and the synthesized events are propagated as native key events except
APZ (because keyboard events are synthesized only in the process). This
behavior allows to test including any default action handlers such as
EventStateManager and setting WidgetGUIEvent::mWidget since some C++ handler
checks if it's nullptr.
Differential Revision: https://phabricator.services.mozilla.com/D5516
--HG--
extra : moz-landing-system : lando
