Provide dummy Android UI thread with looper for C++ unit tests

base/test/test_ui_thread_android.cc

+// Copyright 2015 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.
+#include "base/test/test_ui_thread_android.h"
+
+#include "jni/TestUiThread_jni.h"
+
+namespace base {
+
+void StartTestUiThreadLooper() {
+  Java_TestUiThread_loop(base::android::AttachCurrentThread());
+}
+
+bool RegisterTestUiThreadAndroid(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+}  // namespace base