Revert "Keeps the served view of the window when focus to the ne..."

Revert "Refine FocusHandlingTest"

Revert submission 11182377-fix_b_152373385

Reason for revert: Fix b/155781821
Reverted Changes:
If20cdb43e:Keeps the served view of the window when focus to ...
I50402165b:Refine FocusHandlingTest
Bug: 152373385
Bug: 155781821

Change-Id: I44469caf5a5ceaf247c4e6b0694da9da1f3c0eb1

core/java/android/view/inputmethod/InputMethodManager.java

@@ -645,6 +645,11 @@ public final class InputMethodManager {
         @Override
         public void setCurrentRootView(ViewRootImpl rootView) {
             synchronized (mH) {
+                if (mCurRootView != null) {
+                    // Reset the last served view and restart window focus state of the root view.
+                    mCurRootView.getImeFocusController().setServedView(null);
+                    mRestartOnNextWindowFocus = true;
+                }
                 mCurRootView = rootView;
             }
         }