Converted ActivityAware and ServiceAware Lifecycles to opaque objects (#43670)

ci/licenses_golden/licenses_flutter

@@ -615,6 +615,7 @@ FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/plugin
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/plugins/contentprovider/ContentProviderAware.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/plugins/contentprovider/ContentProviderControlSurface.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/plugins/contentprovider/ContentProviderPluginBinding.java
+FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/plugins/lifecycle/HiddenLifecycleReference.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/plugins/service/ServiceAware.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/plugins/service/ServiceControlSurface.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/plugins/service/ServicePluginBinding.java

shell/platform/android/BUILD.gn

@@ -163,6 +163,7 @@ android_java_sources = [
   "io/flutter/embedding/engine/plugins/contentprovider/ContentProviderAware.java",
   "io/flutter/embedding/engine/plugins/contentprovider/ContentProviderControlSurface.java",
   "io/flutter/embedding/engine/plugins/contentprovider/ContentProviderPluginBinding.java",
+  "io/flutter/embedding/engine/plugins/lifecycle/HiddenLifecycleReference.java",
   "io/flutter/embedding/engine/plugins/service/ServiceAware.java",
   "io/flutter/embedding/engine/plugins/service/ServiceControlSurface.java",
   "io/flutter/embedding/engine/plugins/service/ServicePluginBinding.java",

shell/platform/android/io/flutter/embedding/engine/FlutterEnginePluginRegistry.java

@@ -32,6 +32,7 @@
 import io.flutter.embedding.engine.plugins.contentprovider.ContentProviderAware;
 import io.flutter.embedding.engine.plugins.contentprovider.ContentProviderControlSurface;
 import io.flutter.embedding.engine.plugins.contentprovider.ContentProviderPluginBinding;
+import io.flutter.embedding.engine.plugins.lifecycle.HiddenLifecycleReference;
 import io.flutter.embedding.engine.plugins.service.ServiceAware;
 import io.flutter.embedding.engine.plugins.service.ServiceControlSurface;
 import io.flutter.embedding.engine.plugins.service.ServicePluginBinding;
@@ -535,7 +536,7 @@ private static class FlutterEngineActivityPluginBinding implements ActivityPlugi
     @NonNull
     private final Activity activity;
     @NonNull
-    private final Lifecycle lifecycle;
+    private final HiddenLifecycleReference hiddenLifecycleReference;
     @NonNull
     private final Set<io.flutter.plugin.common.PluginRegistry.RequestPermissionsResultListener> onRequestPermissionsResultListeners = new HashSet<>();
     @NonNull
@@ -549,7 +550,7 @@ private static class FlutterEngineActivityPluginBinding implements ActivityPlugi
 
     public FlutterEngineActivityPluginBinding(@NonNull Activity activity, @NonNull Lifecycle lifecycle) {
       this.activity = activity;
-      this.lifecycle = lifecycle;
+      this.hiddenLifecycleReference = new HiddenLifecycleReference(lifecycle);
     }
 
     @Override
@@ -560,8 +561,8 @@ public Activity getActivity() {
 
     @NonNull
     @Override
-    public Lifecycle getLifecycle() {
-      return lifecycle;
+    public Object getLifecycle() {
+      return hiddenLifecycleReference;
     }
 
     @Override
@@ -685,13 +686,13 @@ private static class FlutterEngineServicePluginBinding implements ServicePluginB
     @NonNull
     private final Service service;
     @Nullable
-    private final Lifecycle lifecycle;
+    private final HiddenLifecycleReference hiddenLifecycleReference;
     @NonNull
     private final Set<ServiceAware.OnModeChangeListener> onModeChangeListeners = new HashSet<>();
 
     FlutterEngineServicePluginBinding(@NonNull Service service, @Nullable Lifecycle lifecycle) {
       this.service = service;
-      this.lifecycle = lifecycle;
+      hiddenLifecycleReference = lifecycle != null ? new HiddenLifecycleReference(lifecycle) : null;
     }
 
     @Override
@@ -702,8 +703,8 @@ public Service getService() {
 
     @Nullable
     @Override
-    public Lifecycle getLifecycle() {
-      return lifecycle;
+    public Object getLifecycle() {
+      return hiddenLifecycleReference;
     }
 
     @Override

shell/platform/android/io/flutter/embedding/engine/plugins/activity/ActivityPluginBinding.java

@@ -5,7 +5,6 @@
 package io.flutter.embedding.engine.plugins.activity;
 
 import android.app.Activity;
-import android.arch.lifecycle.Lifecycle;
 import android.os.Bundle;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
@@ -26,10 +25,17 @@ public interface ActivityPluginBinding {
   Activity getActivity();
 
   /**
-   * Returns the {@link Lifecycle} associated with the attached {@code Activity}.
+   * Returns the {@code Lifecycle} associated with the attached {@code Activity}.
+   * <p>
+   * Use the flutter_plugin_android_lifecycle plugin to turn the returned {@code Object}
+   * into a {@code Lifecycle} object. See
+   * (https://github.com/flutter/plugins/tree/master/packages/flutter_plugin_android_lifecycle).
+   * Flutter plugins that rely on {@code Lifecycle} are forced to use the
+   * flutter_plugin_android_lifecycle plugin so that the version of the Android Lifecycle library is
+   * exposed to pub, which allows Flutter to manage different versions library over time.
    */
   @NonNull
-  Lifecycle getLifecycle();
+  Object getLifecycle();
 
   /**
    * Adds a listener that is invoked whenever the associated {@link Activity}'s

shell/platform/android/io/flutter/embedding/engine/plugins/lifecycle/HiddenLifecycleReference.java

@@ -0,0 +1,33 @@
+// Copyright 2013 The Flutter 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 android.arch.lifecycle.Lifecycle;
+import android.support.annotation.Keep;
+import android.support.annotation.NonNull;
+
+/**
+ * An {@code Object} that can be used to obtain a {@link Lifecycle} reference.
+ * <p>
+ * <strong>DO NOT USE THIS CLASS IN AN APP OR A PLUGIN.</strong>
+ * <p>
+ * This class is used by the flutter_android_lifecycle package to provide access to a
+ * {@link Lifecycle} in a way that makes it easier for Flutter and the Flutter plugin ecosystem to
+ * handle breaking changes in Lifecycle libraries.
+ */
+@Keep
+public class HiddenLifecycleReference {
+  @NonNull
+  private final Lifecycle lifecycle;
+
+  public HiddenLifecycleReference(@NonNull Lifecycle lifecycle) {
+    this.lifecycle = lifecycle;
+  }
+
+  @NonNull
+  public Lifecycle getLifecycle() {
+    return lifecycle;
+  }
+}

shell/platform/android/io/flutter/embedding/engine/plugins/service/ServicePluginBinding.java

@@ -5,7 +5,6 @@
 package io.flutter.embedding.engine.plugins.service;
 
 import android.app.Service;
-import android.arch.lifecycle.Lifecycle;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 
@@ -22,10 +21,17 @@ public interface ServicePluginBinding {
   Service getService();
 
   /**
-   * Returns the {@link Lifecycle} associated with the attached {@code Service}.
+   * Returns the {@code Lifecycle} associated with the attached {@code Service}.
+   * <p>
+   * Use the flutter_plugin_android_lifecycle plugin to turn the returned {@code Object}
+   * into a {@code Lifecycle} object. See
+   * (https://github.com/flutter/plugins/tree/master/packages/flutter_plugin_android_lifecycle).
+   * Flutter plugins that rely on {@code Lifecycle} are forced to use the
+   * flutter_plugin_android_lifecycle plugin so that the version of the Android Lifecycle library is
+   * exposed to pub, which allows Flutter to manage different versions library over time.
    */
   @Nullable
-  Lifecycle getLifecycle();
+  Object getLifecycle();
 
   /**
    * Adds the given {@code listener} to be notified when the associated {@link Service} goes