Change ITestClient to be similar to IChildProcessService.

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

Index: base/test/android/java/src/org/chromium/base/ITestCallback.aidl
diff --git a/base/test/android/java/src/org/chromium/base/ITestCallback.aidl b/base/test/android/java/src/org/chromium/base/ITestCallback.aidl
new file mode 100644
index 0000000000000000000000000000000000000000..48d999432addbe08ad2fe12bcc24b9ee713f16d9
--- /dev/null
+++ b/base/test/android/java/src/org/chromium/base/ITestCallback.aidl
@@ -0,0 +1,16 @@
+// 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.ITestController;
+import org.chromium.base.MainReturnCodeResult;
+import org.chromium.base.process_launcher.FileDescriptorInfo;
+
+/**
+ * This interface is called by the child process to pass its controller to its parent.
+ */
+oneway interface ITestCallback {
+  void childConnected(ITestController controller);
+}