Remove focus if no window and current focus is valid

To prevent the event log report many requesting to set the focus to
null window even the current focus has been cleared.

Bug: 227445061
Test: manual
Change-Id: Ia6b6ff9a50824944788968921274750ad43a4bc8

services/core/java/com/android/server/wm/InputMonitor.java

@@ -414,10 +414,9 @@ final class InputMonitor {
 
         final IBinder focusToken = focus != null ? focus.mInputChannelToken : null;
         if (focusToken == null) {
-            mInputFocus = null;
             // When an app is focused, but its window is not showing yet, remove the input focus
             // from the current window.
-            if (mDisplayContent.mFocusedApp != null) {
+            if (mDisplayContent.mFocusedApp != null && mInputFocus != null) {
                 ProtoLog.v(WM_DEBUG_FOCUS_LIGHT, "App %s is focused,"
                         + " but the window is not ready. Start a transaction to remove focus from"
                         + " the window of non-focused apps.",
@@ -426,6 +425,7 @@ final class InputMonitor {
                         "reason=UpdateInputWindows");
                 mInputTransaction.removeCurrentInputFocus(mDisplayId);
             }
+            mInputFocus = null;
             return;
         }