Skip adding shell drop target window for virtual displays

- Having content on the virtual display can prevent mirroring from
  working correctly

Fixes: 205080647
Test: atest WMShellUnitTests
Change-Id: Id13d8e9020edf5f78c10148f48bd64cec92b7994

libs/WindowManager/Shell/src/com/android/wm/shell/draganddrop/DragAndDropController.java

diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/draganddrop/DragAndDropController.java b/libs/WindowManager/Shell/src/com/android/wm/shell/draganddrop/DragAndDropController.java
index 0c12d6c..d2b4711 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/draganddrop/DragAndDropController.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/draganddrop/DragAndDropController.java
@@ -19,6 +19,7 @@
 import static android.content.ClipDescription.MIMETYPE_APPLICATION_ACTIVITY;
 import static android.content.ClipDescription.MIMETYPE_APPLICATION_SHORTCUT;
 import static android.content.ClipDescription.MIMETYPE_APPLICATION_TASK;
+import static android.view.Display.DEFAULT_DISPLAY;
 import static android.view.DragEvent.ACTION_DRAG_ENDED;
 import static android.view.DragEvent.ACTION_DRAG_ENTERED;
 import static android.view.DragEvent.ACTION_DRAG_EXITED;
@@ -34,13 +35,13 @@
 import static android.view.WindowManager.LayoutParams.SYSTEM_FLAG_SHOW_FOR_ALL_USERS;
 import static android.view.WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY;
 
-import android.content.ClipData;
 import android.content.ClipDescription;
 import android.content.Context;
 import android.content.res.Configuration;
 import android.graphics.PixelFormat;
 import android.util.Slog;
 import android.util.SparseArray;
+import android.view.Display;
 import android.view.DragEvent;
 import android.view.LayoutInflater;
 import android.view.SurfaceControl;
@@ -55,7 +56,6 @@
 import com.android.wm.shell.R;
 import com.android.wm.shell.common.DisplayController;
 import com.android.wm.shell.protolog.ShellProtoLogGroup;
-import com.android.wm.shell.splitscreen.SplitScreen;
 import com.android.wm.shell.splitscreen.SplitScreenController;
 
 import java.util.Optional;
@@ -91,6 +91,11 @@
     @Override
     public void onDisplayAdded(int displayId) {
         ProtoLog.v(ShellProtoLogGroup.WM_SHELL_DRAG_AND_DROP, "Display added: %d", displayId);
+        if (displayId != DEFAULT_DISPLAY) {
+            // Ignore non-default displays for now
+            return;
+        }
+
         final Context context = mDisplayController.getDisplayContext(displayId)
                 .createWindowContext(TYPE_APPLICATION_OVERLAY, null);
         final WindowManager wm = context.getSystemService(WindowManager.class);

libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/draganddrop/DragAndDropControllerTest.java

diff --git a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/draganddrop/DragAndDropControllerTest.java b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/draganddrop/DragAndDropControllerTest.java
new file mode 100644
index 0000000..bfa2c92
--- /dev/null
+++ b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/draganddrop/DragAndDropControllerTest.java
@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.wm.shell.draganddrop;
+
+import static org.junit.Assert.assertFalse;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+
+import android.content.Context;
+import android.os.RemoteException;
+import android.view.Display;
+import android.view.DragEvent;
+import android.view.View;
+
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import androidx.test.filters.SmallTest;
+
+import com.android.internal.logging.UiEventLogger;
+import com.android.wm.shell.common.DisplayController;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+/**
+ * Tests for the drag and drop controller.
+ */
+@SmallTest
+@RunWith(AndroidJUnit4.class)
+public class DragAndDropControllerTest {
+
+    @Mock
+    private Context mContext;
+
+    @Mock
+    private DisplayController mDisplayController;
+
+    @Mock
+    private UiEventLogger mUiEventLogger;
+
+    private DragAndDropController mController;
+
+    @Before
+    public void setUp() throws RemoteException {
+        MockitoAnnotations.initMocks(this);
+
+        mController = new DragAndDropController(mContext, mDisplayController, mUiEventLogger);
+    }
+
+    @Test
+    public void testIgnoreNonDefaultDisplays() {
+        final int nonDefaultDisplayId = 12345;
+        final View dragLayout = mock(View.class);
+        final Display display = mock(Display.class);
+        doReturn(nonDefaultDisplayId).when(display).getDisplayId();
+        doReturn(display).when(dragLayout).getDisplay();
+
+        // Expect no per-display layout to be added
+        mController.onDisplayAdded(nonDefaultDisplayId);
+        assertFalse(mController.onDrag(dragLayout, mock(DragEvent.class)));
+    }
+}