Add plugin for Android lifecycle in embedding

packages/flutter_android_lifecycle/.gitignore

@@ -0,0 +1,7 @@
+.DS_Store
+.dart_tool/
+
+.packages
+.pub/
+
+build/

packages/flutter_android_lifecycle/.metadata

@@ -0,0 +1,10 @@
+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: 0e605cc4dd83137f785769dea5e8ae7da1afb361
+  channel: master
+
+project_type: plugin

packages/flutter_android_lifecycle/CHANGELOG.md

@@ -0,0 +1,4 @@
+## 1.0.0
+
+* Introduces a `FlutterLifecycleAdapter`, which can be used by other plugins to obtain a `Lifecycle`
+  reference from a `FlutterPluginBinding`.

packages/flutter_android_lifecycle/LICENSE

@@ -0,0 +1 @@
+TODO: Add your license here.

packages/flutter_android_lifecycle/README.md

@@ -0,0 +1,41 @@
+# Flutter Android Lifecycle Plugin
+
+[![pub package](https://img.shields.io/pub/v/flutter_android_lifecycle.svg)](https://pub.dartlang.org/packages/flutter_android_lifecycle)
+
+A Flutter plugin for Android to allow other Flutter plugins to access an Android `Lifecycle` object
+in the plugin's binding.
+
+*Note*: This plugin is still under development, and some APIs might not be available yet.
+
+## Installation
+
+Add `flutter_android_lifecycle` as a [dependency in your pubspec.yaml file](https://flutter.io/using-packages/).
+
+## Example
+
+Use a `FlutterLifecycleAdapter` within another Flutter plugin's Android implementation, as shown
+below:
+
+```java
+import androidx.lifecycle.Lifecycle;
+import io.flutter.embedding.engine.FlutterEngine;
+import io.flutter.embedding.engine.plugins.FlutterPlugin;
+import io.flutter.embedding.engine.plugins.FlutterPlugin.FlutterPluginBinding;
+import io.flutter.embedding.engine.plugins.lifecycle.FlutterLifecycleAdapter;
+
+public class MyPlugin implements FlutterPlugin {
+  @Override
+  public void onAttachedToEngine(@NonNull FlutterPluginBinding binding) {
+    Object lifecycleReference = binding.getLifecycle();
+    Lifecycle lifecycle = new FlutterLifecycleAdapter(lifecycleReference).getLifecycle();
+
+    // Use lifecycle as desired.
+  }
+
+  //...
+}
+```
+
+*Note*: This plugin is still under development, and some APIs might not be available yet.
+[Feedback welcome](https://github.com/flutter/flutter/issues) and
+[Pull Requests](https://github.com/flutter/plugins/pulls) are most welcome!

packages/flutter_android_lifecycle/android/.gitignore

@@ -0,0 +1,8 @@
+*.iml
+.gradle
+/local.properties
+/.idea/workspace.xml
+/.idea/libraries
+.DS_Store
+/build
+/captures

packages/flutter_android_lifecycle/android/build.gradle

@@ -0,0 +1,42 @@
+group 'io.flutter.plugins.flutter_android_lifecycle'
+version '1.0'
+
+buildscript {
+    repositories {
+        google()
+        jcenter()
+    }
+
+    dependencies {
+        classpath 'com.android.tools.build:gradle:3.5.0'
+    }
+}
+
+rootProject.allprojects {
+    repositories {
+        google()
+        jcenter()
+    }
+}
+
+apply plugin: 'com.android.library'
+
+android {
+    compileSdkVersion 28
+
+    defaultConfig {
+        minSdkVersion 16
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+    lintOptions {
+        disable 'InvalidPackage'
+    }
+
+    dependencies {
+        implementation "androidx.annotation:annotation:1.1.0"
+        implementation "androidx.lifecycle:lifecycle-runtime:2.0.0-rc01"
+        api 'android.arch.lifecycle:runtime:1.1.1'
+        api 'android.arch.lifecycle:common:1.1.1'
+        api 'android.arch.lifecycle:common-java8:1.1.1'
+    }
+}

packages/flutter_android_lifecycle/android/gradle.properties

@@ -0,0 +1,4 @@
+org.gradle.jvmargs=-Xmx1536M
+android.enableR8=true
+android.useAndroidX=true
+android.enableJetifier=true

packages/flutter_android_lifecycle/android/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.10.2-all.zip

packages/flutter_android_lifecycle/android/settings.gradle

@@ -0,0 +1 @@
+rootProject.name = 'flutter_android_lifecycle'

packages/flutter_android_lifecycle/android/src/main/AndroidManifest.xml

@@ -0,0 +1,3 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+  package="io.flutter.plugins.flutter_android_lifecycle">
+</manifest>

packages/flutter_android_lifecycle/android/src/main/java/io/flutter/embedding/engine/plugins/lifecycle/FlutterLifecycleAdapter.java

@@ -0,0 +1,46 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package io.flutter.embedding.engine.plugins.lifecycle;
+
+import androidx.annotation.NonNull;
+import androidx.lifecycle.Lifecycle;
+import io.flutter.Log;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+
+public class FlutterLifecycleAdapter {
+  private static final String TAG = "FlutterLifecycleAdapter";
+
+  @NonNull private Lifecycle lifecycle = null;
+
+  public FlutterLifecycleAdapter(@NonNull Object reference) {
+    try {
+      Class hiddenLifecycleClass =
+          Class.forName("io.flutter.embedding.engine.plugins.lifecycle.HiddenLifecycleReference");
+
+      if (!reference.getClass().equals(hiddenLifecycleClass)) {
+        throw new IllegalArgumentException(
+            "The reference argument must be of type HiddenLifecycleReference. Was actually "
+                + reference);
+      }
+
+      Method getLifecycle = reference.getClass().getMethod("getLifecycle");
+      this.lifecycle = (Lifecycle) getLifecycle.invoke(reference);
+    } catch (ClassNotFoundException
+        | NoSuchMethodException
+        | IllegalAccessException
+        | InvocationTargetException e) {
+      Log.w(
+          TAG,
+          "You are attempting to use Flutter plugins that are newer than your"
+              + " version of Flutter. Plugins may not work as expected.");
+    }
+  }
+
+  @NonNull
+  public Lifecycle getLifecycle() {
+    return lifecycle;
+  }
+}

packages/flutter_android_lifecycle/android/src/main/java/io/flutter/plugins/flutter_android_lifecycle/FlutterAndroidLifecyclePlugin.java

@@ -0,0 +1,19 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+package io.flutter.plugins.flutter_android_lifecycle;
+
+import io.flutter.plugin.common.PluginRegistry.Registrar;
+
+/**
+ * Plugin class that exists because the Flutter tool expects such a class to exist for every Android
+ * plugin.
+ *
+ * <p><strong>DO NOT USE THIS CLASS.</strong>
+ */
+public class FlutterAndroidLifecyclePlugin {
+  public static void registerWith(Registrar registrar) {
+    // no-op
+  }
+}

packages/flutter_android_lifecycle/example/.gitignore

@@ -0,0 +1,36 @@
+# Miscellaneous
+*.class
+*.log
+*.pyc
+*.swp
+.DS_Store
+.atom/
+.buildlog/
+.history
+.svn/
+
+# IntelliJ related
+*.iml
+*.ipr
+*.iws
+.idea/
+
+# The .vscode folder contains launch configuration and tasks you configure in
+# VS Code which you may wish to be included in version control, so this line
+# is commented out by default.
+#.vscode/
+
+# Flutter/Dart/Pub related
+**/doc/api/
+.dart_tool/
+.flutter-plugins
+.packages
+.pub-cache/
+.pub/
+/build/
+
+# Web related
+lib/generated_plugin_registrant.dart
+
+# Exceptions to above rules.
+!/packages/flutter_tools/test/data/dart_dependencies_test/**/.packages

packages/flutter_android_lifecycle/example/.metadata

@@ -0,0 +1,10 @@
+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: 0e605cc4dd83137f785769dea5e8ae7da1afb361
+  channel: master
+
+project_type: app

packages/flutter_android_lifecycle/example/README.md

@@ -0,0 +1,16 @@
+# flutter_android_lifecycle_example
+
+Demonstrates how to use the flutter_android_lifecycle plugin.
+
+## Getting Started
+
+This project is a starting point for a Flutter application.
+
+A few resources to get you started if this is your first Flutter project:
+
+- [Lab: Write your first Flutter app](https://flutter.dev/docs/get-started/codelab)
+- [Cookbook: Useful Flutter samples](https://flutter.dev/docs/cookbook)
+
+For help getting started with Flutter, view our
+[online documentation](https://flutter.dev/docs), which offers tutorials,
+samples, guidance on mobile development, and a full API reference.

packages/flutter_android_lifecycle/example/android/.gitignore

@@ -0,0 +1,7 @@
+gradle-wrapper.jar
+/.gradle
+/captures/
+/gradlew
+/gradlew.bat
+/local.properties
+GeneratedPluginRegistrant.java

packages/flutter_android_lifecycle/example/android/app/build.gradle

@@ -0,0 +1,61 @@
+def localProperties = new Properties()
+def localPropertiesFile = rootProject.file('local.properties')
+if (localPropertiesFile.exists()) {
+    localPropertiesFile.withReader('UTF-8') { reader ->
+        localProperties.load(reader)
+    }
+}
+
+def flutterRoot = localProperties.getProperty('flutter.sdk')
+if (flutterRoot == null) {
+    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
+}
+
+def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
+if (flutterVersionCode == null) {
+    flutterVersionCode = '1'
+}
+
+def flutterVersionName = localProperties.getProperty('flutter.versionName')
+if (flutterVersionName == null) {
+    flutterVersionName = '1.0'
+}
+
+apply plugin: 'com.android.application'
+apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
+
+android {
+    compileSdkVersion 28
+
+    lintOptions {
+        disable 'InvalidPackage'
+    }
+
+    defaultConfig {
+        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
+        applicationId "io.flutter.plugins.flutter_android_lifecycle_example"
+        minSdkVersion 16
+        targetSdkVersion 28
+        versionCode flutterVersionCode.toInteger()
+        versionName flutterVersionName
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            // TODO: Add your own signing config for the release build.
+            // Signing with the debug keys for now, so `flutter run --release` works.
+            signingConfig signingConfigs.debug
+        }
+    }
+}
+
+flutter {
+    source '../..'
+}
+
+dependencies {
+    testImplementation 'junit:junit:4.12'
+    androidTestImplementation 'androidx.test:runner:1.1.1'
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.1'
+}

packages/flutter_android_lifecycle/example/android/app/src/androidTest/java/io/flutter/plugins/flutter_android_lifecycle_example/EmbeddingV1ActivityTest.java

@@ -0,0 +1,17 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package io.flutter.plugins.flutter_android_lifecycle_example;
+
+import androidx.test.rule.ActivityTestRule;
+import dev.flutter.plugins.e2e.FlutterRunner;
+import org.junit.Rule;
+import org.junit.runner.RunWith;
+
+@RunWith(FlutterRunner.class)
+public class EmbeddingV1ActivityTest {
+  @Rule
+  public ActivityTestRule<EmbeddingV1Activity> rule =
+      new ActivityTestRule<>(EmbeddingV1Activity.class);
+}

packages/flutter_android_lifecycle/example/android/app/src/androidTest/java/io/flutter/plugins/flutter_android_lifecycle_example/MainActivityTest.java

@@ -0,0 +1,15 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package io.flutter.plugins.flutter_android_lifecycle_example;
+
+import androidx.test.rule.ActivityTestRule;
+import dev.flutter.plugins.e2e.FlutterRunner;
+import org.junit.Rule;
+import org.junit.runner.RunWith;
+
+@RunWith(FlutterRunner.class)
+public class MainActivityTest {
+  @Rule public ActivityTestRule<MainActivity> rule = new ActivityTestRule<>(MainActivity.class);
+}

packages/flutter_android_lifecycle/example/android/app/src/debug/AndroidManifest.xml

@@ -0,0 +1,7 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="io.flutter.plugins.flutter_android_lifecycle_example">
+    <!-- Flutter needs it to communicate with the running application
+         to allow setting breakpoints, to provide hot reload, etc.
+    -->
+    <uses-permission android:name="android.permission.INTERNET"/>
+</manifest>