Migrate AutoCompleteTextView to use OnBackInvokedDispatcher.

With ag/17952046 we now actively intercept KEYCODE_BACK before they are
sent to IME when new back flow is used. This requires us to migrate
AutoCompleteTextView#onKeyPreIme, and is also what causes the test
failure in b/231960630.

Test: atest AutoCompleteTextView test.
Test: Test back behavior of AutoCompleteTextView in BackTestApp.
Bug: 231960630
Change-Id: I1a5e01c9a4f8f0e762b493284650854a230aecd3

core/java/android/widget/AutoCompleteTextView.java

@@ -42,6 +42,9 @@ import android.view.inputmethod.CompletionInfo;
 import android.view.inputmethod.EditorInfo;
 import android.view.inputmethod.InputMethodManager;
 import android.view.inspector.InspectableProperty;
+import android.window.OnBackInvokedCallback;
+import android.window.OnBackInvokedDispatcher;
+import android.window.WindowOnBackInvokedDispatcher;
 
 import com.android.internal.R;
 
@@ -143,6 +146,14 @@ public class AutoCompleteTextView extends EditText implements Filter.FilterListe
     @UnsupportedAppUsage
     private PopupDataSetObserver mObserver;
 
+    private boolean mBackCallbackRegistered;
+    /** Handles back invocation */
+    private final OnBackInvokedCallback mBackCallback = () -> {
+        if (isPopupShowing()) {
+            dismissDropDown();
+        }
+    };
+
     /**
      * Constructs a new auto-complete text view with the given context's theme.
      *
@@ -272,6 +283,9 @@ public class AutoCompleteTextView extends EditText implements Filter.FilterListe
         }
 
         mPopup = new ListPopupWindow(mPopupContext, attrs, defStyleAttr, defStyleRes);
+        mPopup.setOnDismissListener(() -> {
+            unregisterOnBackInvokedCallback();
+        });
         mPopup.setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE);
         mPopup.setPromptPosition(ListPopupWindow.POSITION_PROMPT_BELOW);
         mPopup.setListSelector(popupListSelector);
@@ -734,6 +748,7 @@ public class AutoCompleteTextView extends EditText implements Filter.FilterListe
             wrappedListener = new PopupWindow.OnDismissListener() {
                 @Override public void onDismiss() {
                     dismissListener.onDismiss();
+                    unregisterOnBackInvokedCallback();
                 }
             };
         }
@@ -1315,6 +1330,9 @@ public class AutoCompleteTextView extends EditText implements Filter.FilterListe
             mPopup.setListItemExpandMax(EXPAND_MAX);
         }
         mPopup.show();
+        if (!mPopup.isDropDownAlwaysVisible()) {
+            registerOnBackInvokedCallback();
+        }
         mPopup.getListView().setOverScrollMode(View.OVER_SCROLL_ALWAYS);
     }
 
@@ -1414,6 +1432,35 @@ public class AutoCompleteTextView extends EditText implements Filter.FilterListe
         return AutoCompleteTextView.class.getName();
     }
 
+    private void unregisterOnBackInvokedCallback() {
+        if (!mBackCallbackRegistered) {
+            return;
+        }
+        OnBackInvokedDispatcher dispatcher = findOnBackInvokedDispatcher();
+        if (dispatcher == null) {
+            return;
+        }
+        if (WindowOnBackInvokedDispatcher.isOnBackInvokedCallbackEnabled(mPopupContext)) {
+            dispatcher.unregisterOnBackInvokedCallback(mBackCallback);
+        }
+        mBackCallbackRegistered = false;
+    }
+
+    private void registerOnBackInvokedCallback() {
+        if (mBackCallbackRegistered) {
+            return;
+        }
+        OnBackInvokedDispatcher dispatcher =  findOnBackInvokedDispatcher();
+        if (dispatcher == null) {
+            return;
+        }
+        if (WindowOnBackInvokedDispatcher.isOnBackInvokedCallbackEnabled(mPopupContext)) {
+            dispatcher.registerOnBackInvokedCallback(
+                    OnBackInvokedDispatcher.PRIORITY_OVERLAY, mBackCallback);
+        }
+        mBackCallbackRegistered = true;
+    }
+
     private class DropDownItemClickListener implements AdapterView.OnItemClickListener {
         public void onItemClick(AdapterView parent, View v, int position, long id) {
             performCompletion(v, position, id);