As CL[1] introduces diplayContext to address
IME service context's Resources / DisplayMetrics update when
switching IME window to another display after onConfigurationChange.

In LatinIME#onInitializeInterface, we only update keyboard theme context
and displayContent when the displayId is changed, but overlooked even
the displayId is the same, the display context's resource configuration
might changed like the device orientation changd.

It leads getDefaultKeyboardHeight will get wrong config_max_keyboard_height
fraction value when rotating to landcape because the context resources
didn't get updated.

Add a check to update keyboard theme context when the current display
configuation is changed accordingly.

[1]: I0ed6a079af1ed90c75fee1d36d5ce3ef3c41f8ed

Fix: 186507147
Test: manual as issue steps
    1) Turn on auto-rotate
    2) Open Settings
    3) Rotating the device to landscape mode
    4) Tap “Search settings", verify if the soft-keyboard shown and the
       size is expected.
Change-Id: I288a31baf04fa2e63d6b4a14ad81b401cb36ece5