Fix showSoftInput crashing when no IME is enabled

This CL adds a shortcut for bindCurrentMethod in
InputMethodBindingController to return NO_IME instead of
crashing in the rare case when no IME is enabled in the system.

Bug: 220125769
Test: atest InputMethodServiceTest#testShowSoftInput_whenAllImesDisabled
Change-Id: I7da6ed7f2b80331c469751b7091c340422df40a8
(cherry picked from commit 107035849e)
Merged-In:I7da6ed7f2b80331c469751b7091c340422df40a8

services/core/java/com/android/server/inputmethod/InputMethodBindingController.java

@@ -408,6 +408,11 @@ final class InputMethodBindingController {
     @GuardedBy("ImfLock.class")
     @NonNull
     InputBindResult bindCurrentMethod() {
+        if (mSelectedMethodId == null) {
+            Slog.e(TAG, "mSelectedMethodId is null!");
+            return InputBindResult.NO_IME;
+        }
+
         InputMethodInfo info = mMethodMap.get(mSelectedMethodId);
         if (info == null) {
             throw new IllegalArgumentException("Unknown id: " + mSelectedMethodId);