Introduce CommunalSourcePrimer.

CommunalSourcePrimer connects to a pre-defined
CommunalSource at boot if present. It automatically
sets the returned binder as the current
CommunalSource.

Bug: 194354107
Test: manual
Change-Id: I7d1e7abcba2b48d77c9eaaacddb45ba1b3c72f49

packages/SystemUI/res/values/config.xml

@@ -669,4 +669,7 @@
 
     <!-- Whether the communal service should be enabled -->
     <bool name="config_communalServiceEnabled">false</bool>
+
+    <!-- Component name of communal source service -->
+    <string name="config_communalSourceComponent" translatable="false">@null</string>
 </resources>

packages/SystemUI/src/com/android/systemui/communal/service/CommunalSourcePrimer.java

@@ -0,0 +1,105 @@
+/*
+ * 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.systemui.communal.service;
+
+import android.content.ComponentName;
+import android.content.Context;
+import android.content.Intent;
+import android.content.ServiceConnection;
+import android.os.IBinder;
+import android.util.Log;
+
+import com.android.systemui.R;
+import com.android.systemui.SystemUI;
+import com.android.systemui.communal.CommunalSourceMonitor;
+import com.android.systemui.dagger.SysUISingleton;
+import com.android.systemui.dagger.qualifiers.Main;
+import com.android.systemui.shared.communal.ICommunalSource;
+
+import java.util.concurrent.Executor;
+
+import javax.inject.Inject;
+
+/**
+ * The {@link CommunalSourcePrimer} is responsible for priming SystemUI with a pre-configured
+ * Communal source. The SystemUI service binds to the component to retrieve the
+ * {@link com.android.systemui.communal.CommunalSource}. {@link CommunalSourcePrimer} has no effect
+ * if there is no pre-defined value.
+ */
+@SysUISingleton
+public class CommunalSourcePrimer extends SystemUI {
+    private static final String TAG = "CommunalSourcePrimer";
+    private static final boolean DEBUG = false;
+    private final Context mContext;
+    private final Executor mMainExecutor;
+    private final CommunalSourceMonitor mMonitor;
+    private static final String ACTION_COMMUNAL_SOURCE = "android.intent.action.COMMUNAL_SOURCE";
+
+    private final ServiceConnection mConnection = new ServiceConnection() {
+        @Override
+        public void onServiceConnected(ComponentName className, IBinder service) {
+            final ICommunalSource source = ICommunalSource.Stub.asInterface(service);
+            if (DEBUG) {
+                Log.d(TAG, "onServiceConnected. source;" + source);
+            }
+
+            mMonitor.setSource(
+                    source != null ? new CommunalSourceImpl(mMainExecutor, source) : null);
+
+        }
+
+        @Override
+        public void onServiceDisconnected(ComponentName className) {
+        }
+    };
+
+    @Inject
+    public CommunalSourcePrimer(Context context, @Main Executor mainExecutor,
+            CommunalSourceMonitor monitor) {
+        super(context);
+        mContext = context;
+        mMainExecutor = mainExecutor;
+        mMonitor = monitor;
+    }
+
+    @Override
+    public void start() {
+        if (DEBUG) {
+            Log.d(TAG, "start");
+        }
+    }
+
+    @Override
+    protected void onBootCompleted() {
+        super.onBootCompleted();
+        final String serviceComponent = mContext.getString(R.string.config_communalSourceComponent);
+
+        if (DEBUG) {
+            Log.d(TAG, "onBootCompleted. communal source component:" + serviceComponent);
+        }
+
+        if (serviceComponent == null || serviceComponent.isEmpty()) {
+            return;
+        }
+
+        final Intent intent = new Intent();
+        intent.setAction(ACTION_COMMUNAL_SOURCE);
+        intent.setComponent(ComponentName.unflattenFromString(serviceComponent));
+
+        mContext.bindService(intent, mConnection, Context.BIND_AUTO_CREATE);
+    }
+}