Improve performance of proxy resolver by tracing DNS dependencies.

net/net.gyp

Index: net/net.gyp
diff --git a/net/net.gyp b/net/net.gyp
index 749dacad86f7210c07a934efe72ea8e27481b1b3..53f2c0604955f952c01009543c2b8e8e8efe576f 100644
--- a/net/net.gyp
+++ b/net/net.gyp
@@ -628,11 +628,8 @@
         'proxy/proxy_list.h',
         'proxy/proxy_resolver.h',
         'proxy/proxy_resolver_error_observer.h',
-        'proxy/proxy_resolver_js_bindings.cc',
-        'proxy/proxy_resolver_js_bindings.h',
         'proxy/proxy_resolver_mac.cc',
         'proxy/proxy_resolver_mac.h',
-        'proxy/proxy_resolver_request_context.h',
         'proxy/proxy_resolver_script.h',
         'proxy/proxy_resolver_script_data.cc',
         'proxy/proxy_resolver_script_data.h',
@@ -649,9 +646,6 @@
         'proxy/proxy_server_mac.cc',
         'proxy/proxy_service.cc',
         'proxy/proxy_service.h',
-        'proxy/sync_host_resolver.h',
-        'proxy/sync_host_resolver_bridge.cc',
-        'proxy/sync_host_resolver_bridge.h',
         'quic/congestion_control/cubic.cc',
         'quic/congestion_control/cubic.h',
         'quic/congestion_control/fix_rate_receiver.cc',
@@ -1459,13 +1453,12 @@
         'proxy/proxy_config_unittest.cc',
         'proxy/proxy_info_unittest.cc',
         'proxy/proxy_list_unittest.cc',
-        'proxy/proxy_resolver_js_bindings_unittest.cc',
+        'proxy/proxy_resolver_v8_tracing_unittest.cc',
         'proxy/proxy_resolver_v8_unittest.cc',
         'proxy/proxy_script_decider_unittest.cc',
         'proxy/proxy_script_fetcher_impl_unittest.cc',
         'proxy/proxy_server_unittest.cc',
         'proxy/proxy_service_unittest.cc',
-        'proxy/sync_host_resolver_bridge_unittest.cc',
         'quic/congestion_control/cubic_test.cc',
         'quic/congestion_control/fix_rate_test.cc',
         'quic/congestion_control/hybrid_slow_start_test.cc',
@@ -1683,6 +1676,7 @@
           }, {  # else: !use_v8_in_net
             'sources!': [
               'proxy/proxy_resolver_v8_unittest.cc',
+              'proxy/proxy_resolver_v8_tracing_unittest.cc',
             ],
           },
         ],
@@ -2055,6 +2049,8 @@
           'sources': [
             'proxy/proxy_resolver_v8.cc',
             'proxy/proxy_resolver_v8.h',
+            'proxy/proxy_resolver_v8_tracing.cc',
+            'proxy/proxy_resolver_v8_tracing.h',
             'proxy/proxy_service_v8.cc',
             'proxy/proxy_service_v8.h',
           ],