Change I930e9fc85e09e03da3513e5f8443077fa8ea91b0 triggered some NullAway
warnings that are unrelated to the change, but some are trivial to fix,
for example by replacing member variables with local ones.
At the same time, add some `@NonNull` annotations to overriding methods
on Android Studio's recommendation.
Test: check touchpad gesture tutorial and pointer speed settings work
Test: $ atest SettingsRoboTests:com.android.settings.inputmethod
Bug: 245989146
Flag: EXEMPT refactor
Change-Id: I717eb2a2d68a46dce8ebaa95bef1183d09380f51
When we first added the touchpad settings we hadn't settled on whether
to refer to them as "touchpads" or "trackpads" yet. We've since settled
on "touchpad", but that's left us with some Settings code referring to
one and some to the other. Let's standardize on "touchpad" since that's
consistent with user-facing strings and the rest of the input codebase.
This CL doesn't change string identifiers, as I believe that would cause
them to get different Translation Console IDs and thus be retranslated.
Bug: 245989146
Test: m
Test: check strings and icons are still displayed correctly in the
touchpad settings and tutorial, and that settings toggles and the
tutorial still work
Test: atest SettingsRoboTests
Flag: EXEMPT refactor
Change-Id: I930e9fc85e09e03da3513e5f8443077fa8ea91b0
