[Cronet] Clear mock cert verifier reference in CronetEngine.Builder

components/cronet/android/test/javatests/src/org/chromium/net/ChromiumUrlRequestTest.java

 // Copyright 2014 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.net;
 
 import android.test.suitebuilder.annotation.LargeTest;
 import android.test.suitebuilder.annotation.SmallTest;
 
 import org.chromium.base.annotations.SuppressFBWarnings;
@@ skipping 11 matching lines @@
  */
 @SuppressWarnings("deprecation")
 public class ChromiumUrlRequestTest extends CronetTestBase {
     private CronetTestFramework mTestFramework;
     private TestHttpUrlRequestListener mListener;
     private HttpUrlRequest mRequest;
 
     @Override
     protected void setUp() throws Exception {
         super.setUp();
-        mTestFramework = startCronetTestFramework();
+        mTestFramework = startCronetTestFrameworkForLegacyApi(null);
         assertTrue(NativeTestServer.startNativeTestServer(getContext()));
         MockUrlRequestJobFactory.setUp();
     }
 
     @Override
     protected void tearDown() throws Exception {
         NativeTestServer.shutdownNativeTestServer();
         super.tearDown();
     }
 
@@ skipping 255 matching lines @@
         String mockUrl = MockUrlRequestJobFactory.getMockUrlForData(data,
                 repeatCount);
         createRequestAndWaitForComplete(mockUrl, false);
         assertEquals(mockUrl, mListener.mUrl);
         for (int i = 0; i < repeatCount; ++i) {
             assertEquals(data, mListener.mResponseAsString.substring(
                     dataLength * i, dataLength * (i + 1)));
         }
     }
 }