Add chrome perf tests and sniffer to GN build.

chrome/chrome_tests.gypi

 # 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': {
     'chrome_browser_extensions_test_support_sources': [
       # A list of sources which is shared between different browser tests.
       'browser/apps/app_browsertest_util.cc',
       'browser/apps/app_browsertest_util.h',
       'browser/extensions/browsertest_util.cc',
@@ skipping 2856 matching lines @@
       ],
       'include_dirs': [
         '..,'
       ],
     },
   ],
   'conditions': [
     ['OS!="mac"', {
       'targets': [
         {
+          # This test appears to be a legacy target consisting of files not yet
+          # moved elsewhere.
+          #
+          # GN version: //chrome/test/perf
           'target_name': 'perf_tests',
           'type': 'executable',
           'dependencies': [
             'browser',
             'chrome_resources.gyp:chrome_resources',
             'chrome_resources.gyp:chrome_strings',
             'common',
             'renderer',
             '../content/content.gyp:content_gpu',
             '../content/content_shell_and_tests.gyp:test_support_content',
             '../base/base.gyp:base',
             '../base/base.gyp:test_support_base',
             '../base/base.gyp:test_support_perf',
             '../skia/skia.gyp:skia',
             '../testing/gtest.gyp:gtest',
           ],
           'sources': [
+            # Note: Sources list duplicated in GN build.
             'test/perf/perftests.cc',
             'test/perf/url_parse_perftest.cc',
             '../content/browser/net/sqlite_persistent_cookie_store_perftest.cc',
           ],
           'conditions': [
             ['use_x11==1', {
               'dependencies': [
                 '../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
               ],
             }],
@@ skipping 285 matching lines @@
                   ],
                 },
               ],
             }],
           ],
         }],
       ],
     }],
     [ 'enable_mdns == 1', {
       'targets': [{
+          # GN version: //chrome/tools/service_discovery_sniffer
           'target_name': 'service_discovery_sniffer',
           'type': 'executable',
           'dependencies': [
             '../net/net.gyp:net',
             '../base/base.gyp:base',
             '../base/base.gyp:test_support_base',
             'utility',
           ],
           'sources': [
             'tools/service_discovery_sniffer/service_discovery_sniffer.h',
             'tools/service_discovery_sniffer/service_discovery_sniffer.cc',
           ],
           'conditions': [
             ['enable_webrtc==1', {
               'dependencies': [
                 '../third_party/libjingle/libjingle.gyp:libjingle_webrtc'
               ]
             }],
           ],
         }]
     }],
   ],  # 'conditions'
 }