Add BackupTransport#getBackupManagerMonitor

This allows the framework to ask for a monitor to use for backups that
are initiated by the framework (i.e. scheduled backups). Previously
the only way to pass a monitor in was through the
BackupManager#requestBackup API.

I also moved BackupManagerMonitorWrapper to a separate class now that
it's shared by three different classes.

Bug: 252763821
Test: atest CtsBackupHostTestCases
  Also manually by implementing a simple monitor inside LocalTransport
  and calling the new getBackupManagerMonitor.
Change-Id: I84d56a3e80d6c94f9a327f7d71876d1bc27fe5ac

core/java/android/app/backup/BackupManager.java

@@ -29,7 +29,6 @@ import android.content.ComponentName;
 import android.content.Context;
 import android.content.Intent;
 import android.os.Build;
-import android.os.Bundle;
 import android.os.Handler;
 import android.os.Message;
 import android.os.RemoteException;
@@ -1123,18 +1122,4 @@ public class BackupManager {
             });
         }
     }
-
-    private class BackupManagerMonitorWrapper extends IBackupManagerMonitor.Stub {
-        final BackupManagerMonitor mMonitor;
-
-        BackupManagerMonitorWrapper(BackupManagerMonitor monitor) {
-            mMonitor = monitor;
-        }
-
-        @Override
-        public void onEvent(final Bundle event) throws RemoteException {
-            mMonitor.onEvent(event);
-        }
-    }
-
 }

core/java/android/app/backup/BackupManagerMonitorWrapper.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2022 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 android.app.backup;
+
+import android.os.Bundle;
+import android.os.RemoteException;
+
+/**
+ * Wrapper around {@link BackupManagerMonitor} that helps with IPC between the caller of backup
+ * APIs and the backup service.
+ *
+ * The caller implements {@link BackupManagerMonitor} and passes it into framework APIs that run on
+ * the caller's process. Those framework APIs will then wrap it around this class when doing the
+ * actual IPC.
+ */
+class BackupManagerMonitorWrapper extends IBackupManagerMonitor.Stub {
+    private final BackupManagerMonitor mMonitor;
+
+    BackupManagerMonitorWrapper(BackupManagerMonitor monitor) {
+        mMonitor = monitor;
+    }
+
+    @Override
+    public void onEvent(final Bundle event) throws RemoteException {
+        mMonitor.onEvent(event);
+    }
+}

core/java/android/app/backup/BackupTransport.java

@@ -655,6 +655,20 @@ public class BackupTransport {
         return 0;
     }
 
+    /**
+     * Ask the transport for a {@link IBackupManagerMonitor} instance which will be used by the
+     * framework to report logging events back to the transport.
+     *
+     * <p>Backups requested from outside the framework may pass in a monitor with the request,
+     * however backups initiated by the framework will call this method to retrieve one.
+     *
+     * @hide
+     */
+    @Nullable
+    public BackupManagerMonitor getBackupManagerMonitor() {
+        return null;
+    }
+
     /**
      * Bridge between the actual IBackupTransport implementation and the stable API.  If the
      * binder interface needs to change, we use this layer to translate so that we can
@@ -952,5 +966,15 @@ public class BackupTransport {
                 callback.onOperationCompleteWithStatus(BackupTransport.TRANSPORT_ERROR);
             }
         }
+
+        @Override
+        public void getBackupManagerMonitor(AndroidFuture<IBackupManagerMonitor> resultFuture) {
+            try {
+                BackupManagerMonitor result = BackupTransport.this.getBackupManagerMonitor();
+                resultFuture.complete(new BackupManagerMonitorWrapper(result));
+            } catch (RuntimeException e) {
+                resultFuture.cancel(/* mayInterruptIfRunning */ true);
+            }
+        }
     }
 }

core/java/android/app/backup/RestoreSession.java

@@ -20,7 +20,6 @@ import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.annotation.SystemApi;
 import android.content.Context;
-import android.os.Bundle;
 import android.os.Handler;
 import android.os.Message;
 import android.os.RemoteException;
@@ -393,17 +392,4 @@ public class RestoreSession {
                     mHandler.obtainMessage(MSG_RESTORE_FINISHED, error, 0));
         }
     }
-
-    private class BackupManagerMonitorWrapper extends IBackupManagerMonitor.Stub {
-        final BackupManagerMonitor mMonitor;
-
-        BackupManagerMonitorWrapper(BackupManagerMonitor monitor) {
-            mMonitor = monitor;
-        }
-
-        @Override
-        public void onEvent(final Bundle event) throws RemoteException {
-            mMonitor.onEvent(event);
-        }
-    }
 }

core/java/com/android/internal/backup/IBackupTransport.aidl

@@ -16,6 +16,7 @@
 
 package com.android.internal.backup;
 
+import android.app.backup.IBackupManagerMonitor;
 import android.app.backup.RestoreDescription;
 import android.app.backup.RestoreSet;
 import android.content.Intent;
@@ -400,4 +401,13 @@ oneway interface IBackupTransport {
      * <p>For supported flags see {@link android.app.backup.BackupAgent}.
      */
     void getTransportFlags(in AndroidFuture<int> resultFuture);
+
+    /**
+     * Ask the transport for a {@link IBackupManagerMonitor} instance which will be used by the
+     * framework to report logging events back to the transport.
+     *
+     * Backups requested from outside the framework may pass in a monitor with the request,
+     * however backups initiated by the framework will call this method to retrieve one.
+     */
+    void getBackupManagerMonitor(in AndroidFuture<IBackupManagerMonitor> resultFuture);
 }

services/tests/servicestests/src/com/android/server/backup/transport/BackupTransportClientTest.java

@@ -21,6 +21,7 @@ import static com.google.common.truth.Truth.assertThat;
 import static org.junit.Assert.fail;
 
 import android.app.backup.BackupTransport;
+import android.app.backup.IBackupManagerMonitor;
 import android.app.backup.RestoreDescription;
 import android.app.backup.RestoreSet;
 import android.content.Intent;
@@ -254,6 +255,9 @@ public class BackupTransportClientTest {
             ITransportStatusCallback c) throws RemoteException {}
         @Override public void abortFullRestore(ITransportStatusCallback c) throws RemoteException {}
         @Override public void getTransportFlags(AndroidFuture<Integer> f) throws RemoteException {}
+        @Override
+        public void getBackupManagerMonitor(AndroidFuture<IBackupManagerMonitor> resultFuture)
+                throws RemoteException {}
         @Override public IBinder asBinder() {
             return null;
         }