* Shift + swiping space now lets you select text
* Text editor uses more consistent selection logic instead of sending dpad and relying on apps to implement shift+dpad selection, which many of them don't. Dpad is still used for up/down

With CL[1],[2] to migrate InputMethodService as the subclass of the new
introduced class WindowProviderService in S_V2, IME context resources
can be managed by associating the window container of IME window when
its display/window configuration changed.

So we can get rid of createDisplayContext logic from S_V2 with gated
by SDK version and refining the method of get IME context with
documentation to make it clear.

[1]: Ie565e30ed5dd3f2cfe27355a6dded76dc3adc14b
[2]: I64a1614f32d097785915f6105b1813a929e0fe32

Bug: 213118079
Bug: 133825283
Test: manual with below steps
 1) adb install -r EditTextVariations.apk
 2) tapas LatinIME
 3) make
 4) adb install -r out/target/product/generic/system/app/LatinIME/\
        LatinIME.apk
 5) adb shell ime enable com.android.inputmethod.latin/.LatinIME
 6) adb shell ime set com.android.inputmethod.latin/.LatinIME
 5) Enable screen auto-rotation
 7) Launch EditTextVariations from launcher's shortcut
 8) Tap the first EditText field to show IME
 9) Rotate the device to the landscape mode
 10) Expect the IME should not be shrunk

Change-Id: If2cc1c5bdb257a9c0af653fa7157cf781a90bf1d

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
Merged-In: I288a31baf04fa2e63d6b4a14ad81b401cb36ece5