Change the mojo ProxyResolver to use ProxyResolverV8Tracing.

This allows a much simpler implementation of GetLoadState and forwarding
errors to a ProxyResolverErrorObserver as well as enabling a
straightforward implementation of NetLog event reporting.

BUG=467832

Committed: https://crrev.com/9f5bf59b57e6b0662d9b9e0f6715ef7b5af092c0
Cr-Commit-Position: refs/heads/master@{#337993}

Review URL: https://codereview.chromium.org/1166523003

Cr-Commit-Position: refs/heads/master@{#338214}
diff --git a/net/net.gypi b/net/net.gypi
index 630be11..e68ac6b 100644
--- a/net/net.gypi
+++ b/net/net.gypi
@@ -1493,6 +1493,7 @@
       'proxy/dhcp_proxy_script_fetcher_win_unittest.cc',
       'proxy/mojo_proxy_resolver_factory_impl_unittest.cc',
       'proxy/mojo_proxy_resolver_impl_unittest.cc',
+      'proxy/mojo_proxy_resolver_v8_tracing_bindings_unittest.cc',
       'proxy/multi_threaded_proxy_resolver_unittest.cc',
       'proxy/network_delegate_error_observer_unittest.cc',
       'proxy/proxy_bypass_rules_unittest.cc',
@@ -1502,7 +1503,6 @@
       'proxy/proxy_config_unittest.cc',
       'proxy/proxy_info_unittest.cc',
       'proxy/proxy_list_unittest.cc',
-      'proxy/proxy_resolver_error_observer_mojo_unittest.cc',
       'proxy/proxy_resolver_factory_mojo_unittest.cc',
       'proxy/proxy_resolver_v8_tracing_unittest.cc',
       'proxy/proxy_resolver_v8_tracing_wrapper_unittest.cc',