Unifying activity tracker callback

> Using a common class for both Launcher and RecentsActivity
> Removing static refenrece to LauncherModel and using a common pattern for
  tracking activities

Bug: 141376165
Bug: 137568159
Change-Id: Ic1897abe6913ec78e25725118eedf5b468d5ec70

src/com/android/launcher3/util/ObjectWrapper.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2019 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.util;
+
+import android.os.Binder;
+import android.os.IBinder;
+
+/**
+ * Utility class to pass non-parcealable objects within same process using parcealable payload.
+ *
+ * It wraps the object in a binder as binders are singleton within a process
+ */
+public class ObjectWrapper<T> extends Binder {
+
+    private final T mObject;
+
+    public ObjectWrapper(T object) {
+        mObject = object;
+    }
+
+    public T get() {
+        return mObject;
+    }
+
+    public static IBinder wrap(Object obj) {
+        return new ObjectWrapper<>(obj);
+    }
+}