Relanding "Multiprocess test client: Android child process launcher rework."

base/test/android/java/src/org/chromium/base/ITestClient.aidl

+// Copyright 2016 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 org.chromium.base;
+
+import org.chromium.base.FileDescriptorInfo;
+import org.chromium.base.MainReturnCodeResult;
+
+/**
+ * This interface is used to control child processes.
+ */
+interface ITestClient {
+  /**
+   * Runs the native <code>main</code> method in that service's process.
+   * @param args the arguments passed to <code>main</code>
+   * @param fdsToMap a list of file descriptors that are mapped in the native code
+   * in <code>base::GlobalDescriptors</code>.
+   * @return the process ID for the service's process.
+   */
+  int launch(in String[] args, in FileDescriptorInfo[] fdsToMap);
+
+  /**
+   * Blocks until the <code>main</code> method started with {@link #launch()} returns, or returns
+   * immediately if main has already returned.
+   * @param timeoutMs time in milliseconds after which this method returns even if the main method
+   * has not returned yet.
+   * @return a result containing whether a timeout occured and the value returned by the
+   * <code>main</code> method
+   */
+  MainReturnCodeResult waitForMainToReturn(int timeoutMs);
+
+  /**
+   * Forces the service process to terminate and block until the process stops.
+   * @param exitCode the exit code the process should terminate with.
+   * @return always true, a return value is only returned to force the call to be synchronous.
+   */
+  boolean forceStopSynchronous(int exitCode);
+
+  /**
+   * Forces the service process to terminate.
+   * @param exitCode the exit code the process should terminate with.
+   */
+  void forceStop(int exitCode);
+}