android: Java-based launcher thread

content/browser/android/launcher_thread.cc

+// Copyright 2017 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 "content/browser/android/launcher_thread.h"
+
+#include "jni/LauncherThread_jni.h"
+
+namespace content {
+namespace android {
+
+namespace {
+base::LazyInstance<LauncherThread>::Leaky g_launcher_thread;
+}
+
+base::MessageLoop* LauncherThread::GetMessageLoop() {
+  return g_launcher_thread.Get().java_handler_thread_.message_loop();
+}
+
+LauncherThread::LauncherThread()
+    : java_handler_thread_(Java_LauncherThread_getHandlerThread(
+          base::android::AttachCurrentThread())) {}
+
+LauncherThread::~LauncherThread() {}
+
+}  // namespace android
+}  // namespace content