Implement DisplayWindowPolicyController

Implement DisplayWindowPolicyController to control the policies of the
windows that can be displayed on the virtual display.

Bug: 201712607
Test: manual
Change-Id: Ie7f947cfa79d54a86badd81c8339a09c53a87b3c

services/companion/Android.bp

@@ -24,5 +24,8 @@ java_library_static {
         type: "stream",
     },
     srcs: [":services.companion-sources"],
-    libs: ["services.core"],
+    libs: [
+        "app-compat-annotations",
+        "services.core",
+    ],
 }

services/companion/java/com/android/server/companion/virtual/GenericWindowPolicyController.java

@@ -0,0 +1,94 @@
+/*
+ * Copyright (C) 2021 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.server.companion.virtual;
+
+import static android.view.WindowManager.LayoutParams.FLAG_SECURE;
+import static android.view.WindowManager.LayoutParams.SYSTEM_FLAG_HIDE_NON_SYSTEM_OVERLAY_WINDOWS;
+
+import android.annotation.NonNull;
+import android.app.compat.CompatChanges;
+import android.compat.annotation.ChangeId;
+import android.compat.annotation.EnabledSince;
+import android.content.ComponentName;
+import android.content.pm.ActivityInfo;
+import android.os.Build;
+import android.os.UserHandle;
+import android.window.DisplayWindowPolicyController;
+
+import java.util.List;
+
+
+/**
+ * A controller to control the policies of the windows that can be displayed on the virtual display.
+ */
+class GenericWindowPolicyController extends DisplayWindowPolicyController {
+
+    /**
+     * If required, allow the secure activity to display on remote device since
+     * {@link android.os.Build.VERSION_CODES#TIRAMISU}.
+     */
+    @ChangeId
+    @EnabledSince(targetSdkVersion = Build.VERSION_CODES.TIRAMISU)
+    public static final long ALLOW_SECURE_ACTIVITY_DISPLAY_ON_REMOTE_DEVICE = 201712607L;
+
+    GenericWindowPolicyController(int windowFlags, int systemWindowFlags) {
+        setInterestedWindowFlags(windowFlags, systemWindowFlags);
+    }
+
+    @Override
+    public boolean canContainActivities(@NonNull List<ActivityInfo> activities) {
+        // Can't display all the activities if any of them don't want to be displayed.
+        final int activityCount = activities.size();
+        for (int i = 0; i < activityCount; i++) {
+            final ActivityInfo aInfo = activities.get(i);
+            if ((aInfo.flags & ActivityInfo.FLAG_CAN_DISPLAY_ON_REMOTE_DEVICES) == 0) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    @Override
+    public boolean keepActivityOnWindowFlagsChanged(ActivityInfo activityInfo, int windowFlags,
+            int systemWindowFlags) {
+        if ((activityInfo.flags & ActivityInfo.FLAG_CAN_DISPLAY_ON_REMOTE_DEVICES) == 0) {
+            return false;
+        }
+        if (!CompatChanges.isChangeEnabled(ALLOW_SECURE_ACTIVITY_DISPLAY_ON_REMOTE_DEVICE,
+                activityInfo.packageName,
+                UserHandle.getUserHandleForUid(activityInfo.applicationInfo.uid))) {
+            // TODO(b/201712607): Add checks for the apps that use SurfaceView#setSecure.
+            if ((windowFlags & FLAG_SECURE) != 0) {
+                return false;
+            }
+            if ((systemWindowFlags & SYSTEM_FLAG_HIDE_NON_SYSTEM_OVERLAY_WINDOWS) != 0) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    @Override
+    public void onTopActivityChanged(ComponentName topActivity, int uid) {
+
+    }
+
+    @Override
+    public void onRunningAppsChanged(int[] runningUids) {
+
+    }
+}

services/companion/java/com/android/server/companion/virtual/VirtualDeviceManagerService.java

@@ -16,6 +16,9 @@
 
 package com.android.server.companion.virtual;
 
+import static android.view.WindowManager.LayoutParams.FLAG_SECURE;
+import static android.view.WindowManager.LayoutParams.SYSTEM_FLAG_HIDE_NON_SYSTEM_OVERLAY_WINDOWS;
+
 import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.annotation.SuppressLint;
@@ -131,11 +134,14 @@ public class VirtualDeviceManagerService extends SystemService {
 
         private final AssociationInfo mAssociationInfo;
         private final int mOwnerUid;
+        private final GenericWindowPolicyController mGenericWindowPolicyController;
         private final ArrayList<Integer> mDisplayIds = new ArrayList<>();
 
         private VirtualDeviceImpl(int ownerUid, IBinder token, AssociationInfo associationInfo) {
             mOwnerUid = ownerUid;
             mAssociationInfo = associationInfo;
+            mGenericWindowPolicyController = new GenericWindowPolicyController(FLAG_SECURE,
+                    SYSTEM_FLAG_HIDE_NON_SYSTEM_OVERLAY_WINDOWS);
             try {
                 token.linkToDeath(this, 0);
             } catch (RemoteException e) {
@@ -167,8 +173,7 @@ public class VirtualDeviceManagerService extends SystemService {
                         "Virtual device already have a virtual display with ID " + displayId);
             }
             mDisplayIds.add(displayId);
-            // TODO(b/201712607): Return the corresponding DisplayWindowPolicyController.
-            return null;
+            return mGenericWindowPolicyController;
         }
 
         void onVirtualDisplayRemovedLocked(int displayId) {