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/PinnedAppListViewModel.java

@@ -0,0 +1,120 @@
+/**
+ * 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 static com.android.launcher3.PinnedAppListViewModel.PINNED_APPS_KEY;
+
+import android.app.Application;
+import android.content.ComponentName;
+import android.content.Context;
+import android.content.Intent;
+import android.content.SharedPreferences;
+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;
+import java.util.Set;
+
+/**
+ * A view model that provides a list of activities that were pinned by user to always display on
+ * home screen.
+ * The pinned activities are stored in {@link SharedPreferences} to keep the sample simple :).
+ */
+public class PinnedAppListViewModel extends AndroidViewModel {
+
+    final static String PINNED_APPS_KEY = "pinned_apps";
+
+    private final PinnedAppListLiveData mLiveData;
+
+    public PinnedAppListViewModel(Application application) {
+        super(application);
+        mLiveData = new PinnedAppListLiveData(application);
+    }
+
+    public LiveData<List<AppEntry>> getPinnedAppList() {
+        return mLiveData;
+    }
+}
+
+class PinnedAppListLiveData extends LiveData<List<AppEntry>> {
+
+    private final Context mContext;
+    private final PackageManager mPackageManager;
+    // Store listener reference, so it won't be GC-ed.
+    private final SharedPreferences.OnSharedPreferenceChangeListener mChangeListener;
+    private int mCurrentDataVersion;
+
+    public PinnedAppListLiveData(Context context) {
+        mContext = context;
+        mPackageManager = context.getPackageManager();
+
+        final SharedPreferences prefs = context.getSharedPreferences(PINNED_APPS_KEY, 0);
+        mChangeListener = (preferences, key) -> {
+            loadData();
+        };
+        prefs.registerOnSharedPreferenceChangeListener(mChangeListener);
+
+        loadData();
+    }
+
+    private void loadData() {
+        final int loadDataVersion = ++mCurrentDataVersion;
+
+        new AsyncTask<Void, Void, List<AppEntry>>() {
+            @Override
+            protected List<AppEntry> doInBackground(Void... voids) {
+                List<AppEntry> entries = new ArrayList<>();
+
+                final SharedPreferences sp = mContext.getSharedPreferences(PINNED_APPS_KEY, 0);
+                final Set<String> pinnedAppsComponents = sp.getStringSet(PINNED_APPS_KEY, null);
+                if (pinnedAppsComponents == null) {
+                    return null;
+                }
+
+                for (String componentString : pinnedAppsComponents) {
+                    final Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
+                    mainIntent.setComponent(ComponentName.unflattenFromString(componentString));
+                    mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);
+
+                    final List<ResolveInfo> apps = mPackageManager.queryIntentActivities(mainIntent,
+                            PackageManager.GET_META_DATA);
+
+                    if (apps != null) {
+                        for (ResolveInfo app : apps) {
+                            final AppEntry entry = new AppEntry(app, mPackageManager);
+                            entries.add(entry);
+                        }
+                    }
+                }
+
+                return entries;
+            }
+
+            @Override
+            protected void onPostExecute(List<AppEntry> data) {
+                if (mCurrentDataVersion == loadDataVersion) {
+                    setValue(data);
+                }
+            }
+        }.execute();
+    }
+}