Fix the logic that decides whether to use currentRequestThreadFactory() under App Engine.

While there, also support thread renaming under App Engine.

Fixes #3598
Relevant to #3606
(also, the CL in which I experimented with #3569 before backing it out)

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=272446666

Author: cpovirk

android/guava/src/com/google/common/util/concurrent/Callables.java

@@ -129,9 +129,10 @@ public void run() {
   /** Tries to set name of the given {@link Thread}, returns true if successful. */
   @GwtIncompatible // threads
   private static boolean trySetName(final String threadName, Thread currentThread) {
-    // In AppEngine, this will always fail. Should we test for that explicitly using
-    // MoreExecutors.isAppEngine? More generally, is there a way to see if we have the modifyThread
-    // permission without catching an exception?
+    /*
+     * setName should usually succeed, but the security manager can prohibit it. Is there a way to
+     * see if we have the modifyThread permission without catching an exception?
+     */
     try {
       currentThread.setName(threadName);
       return true;

android/guava/src/com/google/common/util/concurrent/MoreExecutors.java

@@ -739,15 +739,17 @@ public void run() {
   /**
    * Returns a default thread factory used to create new threads.
    *
-   * <p>On AppEngine, returns {@code ThreadManager.currentRequestThreadFactory()}. Otherwise,
-   * returns {@link Executors#defaultThreadFactory()}.
+   * <p>When running on AppEngine with access to <a
+   * href="https://cloud.google.com/appengine/docs/standard/java/javadoc/">AppEngine legacy
+   * APIs</a>, this method returns {@code ThreadManager.currentRequestThreadFactory()}. Otherwise,
+   * it returns {@link Executors#defaultThreadFactory()}.
    *
    * @since 14.0
    */
   @Beta
   @GwtIncompatible // concurrency
   public static ThreadFactory platformThreadFactory() {
-    if (!isAppEngine()) {
+    if (!isAppEngineWithApiClasses()) {
       return Executors.defaultThreadFactory();
     }
     try {
@@ -772,10 +774,15 @@ public static ThreadFactory platformThreadFactory() {
   }
 
   @GwtIncompatible // TODO
-  private static boolean isAppEngine() {
+  private static boolean isAppEngineWithApiClasses() {
     if (System.getProperty("com.google.appengine.runtime.environment") == null) {
       return false;
     }
+    try {
+      Class.forName("com.google.appengine.api.utils.SystemProperty");
+    } catch (ClassNotFoundException e) {
+      return false;
+    }
     try {
       // If the current environment is null, we're not inside AppEngine.
       return Class.forName("com.google.apphosting.api.ApiProxy")
@@ -833,10 +840,6 @@ static Thread newThread(String name, Runnable runnable) {
   static Executor renamingDecorator(final Executor executor, final Supplier<String> nameSupplier) {
     checkNotNull(executor);
     checkNotNull(nameSupplier);
-    if (isAppEngine()) {
-      // AppEngine doesn't support thread renaming, so don't even try
-      return executor;
-    }
     return new Executor() {
       @Override
       public void execute(Runnable command) {
@@ -862,10 +865,6 @@ static ExecutorService renamingDecorator(
       final ExecutorService service, final Supplier<String> nameSupplier) {
     checkNotNull(service);
     checkNotNull(nameSupplier);
-    if (isAppEngine()) {
-      // AppEngine doesn't support thread renaming, so don't even try.
-      return service;
-    }
     return new WrappingExecutorService(service) {
       @Override
       protected <T> Callable<T> wrapTask(Callable<T> callable) {
@@ -896,10 +895,6 @@ static ScheduledExecutorService renamingDecorator(
       final ScheduledExecutorService service, final Supplier<String> nameSupplier) {
     checkNotNull(service);
     checkNotNull(nameSupplier);
-    if (isAppEngine()) {
-      // AppEngine doesn't support thread renaming, so don't even try.
-      return service;
-    }
     return new WrappingScheduledExecutorService(service) {
       @Override
       protected <T> Callable<T> wrapTask(Callable<T> callable) {

guava-gwt/test/com/google/common/util/concurrent/testModule.gwt.xml

@@ -9,6 +9,7 @@
   <inherits name="com.google.common.testing.Testing"/>
   <inherits name="com.google.common.util.concurrent.Concurrent"/>
   <inherits name="com.google.common.truth.Truth"/>
+  <inherits name="activation.Activation"/>
   <entry-point class="com.google.common.util.concurrent.TestModuleEntryPoint"/>
 
   <source path=""/>

guava/src/com/google/common/util/concurrent/Callables.java

@@ -129,9 +129,10 @@ public void run() {
   /** Tries to set name of the given {@link Thread}, returns true if successful. */
   @GwtIncompatible // threads
   private static boolean trySetName(final String threadName, Thread currentThread) {
-    // In AppEngine, this will always fail. Should we test for that explicitly using
-    // MoreExecutors.isAppEngine? More generally, is there a way to see if we have the modifyThread
-    // permission without catching an exception?
+    /*
+     * setName should usually succeed, but the security manager can prohibit it. Is there a way to
+     * see if we have the modifyThread permission without catching an exception?
+     */
     try {
       currentThread.setName(threadName);
       return true;

guava/src/com/google/common/util/concurrent/MoreExecutors.java

@@ -814,15 +814,17 @@ public void run() {
   /**
    * Returns a default thread factory used to create new threads.
    *
-   * <p>On AppEngine, returns {@code ThreadManager.currentRequestThreadFactory()}. Otherwise,
-   * returns {@link Executors#defaultThreadFactory()}.
+   * <p>When running on AppEngine with access to <a
+   * href="https://cloud.google.com/appengine/docs/standard/java/javadoc/">AppEngine legacy
+   * APIs</a>, this method returns {@code ThreadManager.currentRequestThreadFactory()}. Otherwise,
+   * it returns {@link Executors#defaultThreadFactory()}.
    *
    * @since 14.0
    */
   @Beta
   @GwtIncompatible // concurrency
   public static ThreadFactory platformThreadFactory() {
-    if (!isAppEngine()) {
+    if (!isAppEngineWithApiClasses()) {
       return Executors.defaultThreadFactory();
     }
     try {
@@ -847,10 +849,15 @@ public static ThreadFactory platformThreadFactory() {
   }
 
   @GwtIncompatible // TODO
-  private static boolean isAppEngine() {
+  private static boolean isAppEngineWithApiClasses() {
     if (System.getProperty("com.google.appengine.runtime.environment") == null) {
       return false;
     }
+    try {
+      Class.forName("com.google.appengine.api.utils.SystemProperty");
+    } catch (ClassNotFoundException e) {
+      return false;
+    }
     try {
       // If the current environment is null, we're not inside AppEngine.
       return Class.forName("com.google.apphosting.api.ApiProxy")
@@ -908,10 +915,6 @@ static Thread newThread(String name, Runnable runnable) {
   static Executor renamingDecorator(final Executor executor, final Supplier<String> nameSupplier) {
     checkNotNull(executor);
     checkNotNull(nameSupplier);
-    if (isAppEngine()) {
-      // AppEngine doesn't support thread renaming, so don't even try
-      return executor;
-    }
     return new Executor() {
       @Override
       public void execute(Runnable command) {
@@ -937,10 +940,6 @@ static ExecutorService renamingDecorator(
       final ExecutorService service, final Supplier<String> nameSupplier) {
     checkNotNull(service);
     checkNotNull(nameSupplier);
-    if (isAppEngine()) {
-      // AppEngine doesn't support thread renaming, so don't even try.
-      return service;
-    }
     return new WrappingExecutorService(service) {
       @Override
       protected <T> Callable<T> wrapTask(Callable<T> callable) {
@@ -971,10 +970,6 @@ static ScheduledExecutorService renamingDecorator(
       final ScheduledExecutorService service, final Supplier<String> nameSupplier) {
     checkNotNull(service);
     checkNotNull(nameSupplier);
-    if (isAppEngine()) {
-      // AppEngine doesn't support thread renaming, so don't even try.
-      return service;
-    }
     return new WrappingScheduledExecutorService(service) {
       @Override
       protected <T> Callable<T> wrapTask(Callable<T> callable) {