Fix IME hide state

Insets API notifies IME when it's hidden. however, IMMS never
really received these state changes. Using requestHideSelf() makes sure
IMMS is in-sync.

Fix: 151980214
Test: manually using the steps in bug

Change-Id: I7f6098a61a5942795ffd33a60329e4dd5fb5d6cb
diff --git a/core/java/android/inputmethodservice/InputMethodService.java b/core/java/android/inputmethodservice/InputMethodService.java
index c2ee21d..7c34ddc 100644
--- a/core/java/android/inputmethodservice/InputMethodService.java
+++ b/core/java/android/inputmethodservice/InputMethodService.java
@@ -878,7 +878,7 @@
     }
 
     private void notifyImeHidden() {
-        doHideWindow();
+        requestHideSelf(0);
     }
 
     private void removeImeSurface() {