Add experiment to measure time to hash extension content as we read it

net/net.gyp

 # Copyright 2013 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.
 
 {
   'variables': {
     'chromium_code': 1,
 
     'linux_link_kerberos%': 0,
     'use_tracing_cache_backend%': 0,
@@ skipping 2081 matching lines @@
         'tools/dump_cache/url_to_filename_encoder.h',
         'tools/dump_cache/url_to_filename_encoder_unittest.cc',
         'tools/dump_cache/url_utilities.h',
         'tools/dump_cache/url_utilities.cc',
         'tools/dump_cache/url_utilities_unittest.cc',
         'tools/tld_cleanup/tld_cleanup_util_unittest.cc',
         'udp/udp_socket_unittest.cc',
         'url_request/url_fetcher_impl_unittest.cc',
         'url_request/url_fetcher_response_writer_unittest.cc',
         'url_request/url_request_context_builder_unittest.cc',
+        'url_request/url_request_file_job_unittest.cc',
         'url_request/url_request_filter_unittest.cc',
         'url_request/url_request_ftp_job_unittest.cc',
         'url_request/url_request_http_job_unittest.cc',
         'url_request/url_request_job_factory_impl_unittest.cc',
         'url_request/url_request_job_unittest.cc',
         'url_request/url_request_simple_job_unittest.cc',
         'url_request/url_request_throttler_simulation_unittest.cc',
         'url_request/url_request_throttler_test_support.cc',
         'url_request/url_request_throttler_test_support.h',
         'url_request/url_request_throttler_unittest.cc',
@@ skipping 1299 matching lines @@
             'java_in_dir': 'cronet/android/sample/javatests',
             'resource_dir': 'cronet/android/sample/res',
             'is_test_apk': 1,
           },
           'includes': [ '../build/java_apk.gypi' ],
         },
       ],
     }],  # OS=="android"
   ],
 }