Add net library for content unit test and enable related test cases on Android.

content/test/run_all_unittests.cc

 // Copyright (c) 2012 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/test/content_test_suite.h"
 #include "content/public/test/unittest_test_suite.h"
 
 #if defined(OS_ANDROID)
 #include "base/android/jni_android.h"
 #include "content/browser/android/browser_jni_registrar.h"
 #include "content/common/android/common_jni_registrar.h"
+#include "net/android/net_jni_registrar.h"
 #endif
 
 int main(int argc, char** argv) {
 
 #if defined(OS_ANDROID)
   // Register JNI bindings for android.
   JNIEnv* env = base::android::AttachCurrentThread();
   content::android::RegisterCommonJni(env);
   content::android::RegisterBrowserJni(env);
+  net::android::RegisterJni(env);
 #endif
 
   return content::UnitTestTestSuite(
       new content::ContentTestSuite(argc, argv)).Run();
 }