[Android Webview] Refactor LoadUrlTest and work on embedded_test_server custom handler

android_webview/test/embedded_test_server/aw_test_entry_point.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 "android_webview/test/embedded_test_server/aw_test_jni_onload.h"
+#include "base/android/jni_android.h"
+
+// This is called by the VM when the shared library is first loaded.
+JNI_EXPORT jint JNI_OnLoad(JavaVM* vm, void* reserved) {
+  base::android::InitVM(vm);
+  JNIEnv* env = base::android::AttachCurrentThread();
+  if (!android_webview::test::OnJNIOnLoadRegisterJNI(env) ||
+      !android_webview::test::OnJNIOnLoadInit()) {
+    return -1;
+  }
+  return JNI_VERSION_1_4;
+}