Adds UMA to measure when the data reduction proxy via header is missing

components/data_reduction_proxy.gypi

 # 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.
 
 
 {
   'targets': [
     {
       # GN version: //components/data_reduction_proxy/browser
       'target_name': 'data_reduction_proxy_browser',
@@ skipping 71 matching lines @@
       ],
       'include_dirs': [
         '..',
       ],
       'sources': [
         # Note: sources list duplicated in GN build.
         'data_reduction_proxy/browser/data_reduction_proxy_params_test_utils.cc',
         'data_reduction_proxy/browser/data_reduction_proxy_params_test_utils.h',
         'data_reduction_proxy/browser/data_reduction_proxy_settings_test_utils.cc',
         'data_reduction_proxy/browser/data_reduction_proxy_settings_test_utils.h',
+        'data_reduction_proxy/common/data_reduction_proxy_headers_test_utils.cc',
+        'data_reduction_proxy/common/data_reduction_proxy_headers_test_utils.h',
       ],
     },
     {
       'target_name': 'data_reduction_proxy_version_header',
       'type': 'none',
       'direct_dependent_settings': {
         'include_dirs': [
           '<(SHARED_INTERMEDIATE_DIR)',
         ],
       },
@@ skipping 18 matching lines @@
           'includes': [
             '../build/util/version.gypi',
           ],
         },
       ],
     },
 
   ],
 }