Initial checkin of AOSP Messaging app.

b/23110861

Change-Id: I11db999bd10656801e618f78ab2b2ef74136fff1

src/com/android/messaging/ui/PagerViewHolder.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2015 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.messaging.ui;
+
+import android.view.View;
+import android.view.ViewGroup;
+
+/**
+ * Holds reusable View(s) for a {@link FixedViewPagerAdapter} to display a page. By using
+ * reusable Views inside ViewPagers this allows us to get rid of nested fragments and the messy
+ * activity lifecycle problems they entail.
+ */
+public interface PagerViewHolder extends PersistentInstanceState {
+    /** Instructs the pager to clean up any view related resources
+     * @return the destroyed View so that the adapter may remove it from the container, or
+     * null if no View has been created. */
+    View destroyView();
+
+    /** @return The view that presents the page view to the user */
+    View getView(ViewGroup container);
+}