Add a secondary launcher activity (1/2)

This secondary launcher activity with new category SECONDARY_HOME and
multiple instance supporrted could be used on sencondary display.

Bug: 118206886
Bug: 114329798
Test: Manual
Change-Id: Ibaecf8ef7614389760d0fcc547ef6d378a921583

SecondaryDisplayLauncher/src/com/android/launcher3/AppListViewModel.java

@@ -0,0 +1,126 @@
+/**
+ * Copyright (c) 2018 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.launcher3;
+
+import android.app.Application;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.content.pm.PackageManager;
+import android.content.pm.ResolveInfo;
+import android.os.AsyncTask;
+
+import androidx.lifecycle.AndroidViewModel;
+import androidx.lifecycle.LiveData;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * A view model that provides a list of activities that can be launched.
+ */
+public class AppListViewModel extends AndroidViewModel {
+
+    private final AppListLiveData mLiveData;
+    private final PackageIntentReceiver
+            mPackageIntentReceiver;
+
+    public AppListViewModel(Application application) {
+        super(application);
+        mLiveData = new AppListLiveData(application);
+        mPackageIntentReceiver = new PackageIntentReceiver(mLiveData, application);
+    }
+
+    public LiveData<List<AppEntry>> getAppList() {
+        return mLiveData;
+    }
+
+    protected void onCleared() {
+        getApplication().unregisterReceiver(mPackageIntentReceiver);
+    }
+}
+
+class AppListLiveData extends LiveData<List<AppEntry>> {
+
+    private final PackageManager mPackageManager;
+    private int mCurrentDataVersion;
+
+    public AppListLiveData(Context context) {
+        mPackageManager = context.getPackageManager();
+        loadData();
+    }
+
+    void loadData() {
+        final int loadDataVersion = ++mCurrentDataVersion;
+
+        new AsyncTask<Void, Void, List<AppEntry>>() {
+            @Override
+            protected List<AppEntry> doInBackground(Void... voids) {
+                Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
+                mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);
+
+                List<ResolveInfo> apps = mPackageManager.queryIntentActivities(mainIntent,
+                        PackageManager.GET_META_DATA);
+
+                List<AppEntry> entries = new ArrayList<>();
+                if (apps != null) {
+                    for (ResolveInfo app : apps) {
+                        AppEntry entry = new AppEntry(app, mPackageManager);
+                        entries.add(entry);
+                    }
+                }
+                return entries;
+            }
+
+            @Override
+            protected void onPostExecute(List<AppEntry> data) {
+                if (mCurrentDataVersion == loadDataVersion) {
+                    setValue(data);
+                }
+            }
+        }.execute();
+    }
+}
+
+/**
+ * Receiver used to notify live data about app list changes.
+ */
+class PackageIntentReceiver extends BroadcastReceiver {
+
+    private final AppListLiveData mLiveData;
+
+    public PackageIntentReceiver(AppListLiveData liveData, Context context) {
+        mLiveData = liveData;
+        IntentFilter filter = new IntentFilter(Intent.ACTION_PACKAGE_ADDED);
+        filter.addAction(Intent.ACTION_PACKAGE_REMOVED);
+        filter.addAction(Intent.ACTION_PACKAGE_CHANGED);
+        filter.addDataScheme("package");
+        context.registerReceiver(this, filter);
+
+        // Register for events related to sdcard installation.
+        IntentFilter sdFilter = new IntentFilter();
+        sdFilter.addAction(Intent.ACTION_EXTERNAL_APPLICATIONS_AVAILABLE);
+        sdFilter.addAction(Intent.ACTION_EXTERNAL_APPLICATIONS_UNAVAILABLE);
+        context.registerReceiver(this, sdFilter);
+    }
+
+    @Override
+    public void onReceive(Context context, Intent intent) {
+        mLiveData.loadData();
+    }
+}