Create ContentShellActivityTestRule and BaseJUnitRunner

base/test/android/javatests/src/org/chromium/base/test/BaseJUnitRunner.java

+// 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.
+
+package org.chromium.base.test;
+
+import android.os.Bundle;
+import android.support.test.runner.AndroidJUnitRunner;
+
+import org.chromium.base.multidex.ChromiumMultiDexInstaller;
+
+/**
+ *  A custom runner for JUnit4 tests that checks requirements to conditionally ignore tests.
+ */
+public class BaseJUnitRunner extends AndroidJUnitRunner {
+    @Override
+    public void onCreate(Bundle arguments) {
+        ChromiumMultiDexInstaller.install(getTargetContext());
+        super.onCreate(arguments);
+    }
+}