Add ProxyResolverFactoryV8Tracing.

net/proxy/mojo_proxy_resolver_factory_impl.cc

Index: net/proxy/mojo_proxy_resolver_factory_impl.cc
diff --git a/net/proxy/mojo_proxy_resolver_factory_impl.cc b/net/proxy/mojo_proxy_resolver_factory_impl.cc
index 9134495ba3f46157ef127657c47730a3a5f7523e..1bcd1ced201f156927c5a207a4a002b82641c5f2 100644
--- a/net/proxy/mojo_proxy_resolver_factory_impl.cc
+++ b/net/proxy/mojo_proxy_resolver_factory_impl.cc
@@ -10,6 +10,7 @@
 #include "net/base/net_errors.h"
 #include "net/dns/host_resolver_mojo.h"
 #include "net/proxy/mojo_proxy_resolver_impl.h"
+#include "net/proxy/proxy_resolver_error_observer.h"
 #include "net/proxy/proxy_resolver_factory.h"
 #include "net/proxy/proxy_resolver_v8.h"
 #include "net/proxy/proxy_resolver_v8_tracing.h"
@@ -18,23 +19,17 @@
 namespace net {
 namespace {
 
-class DefaultProxyResolverFactory : public LegacyProxyResolverFactory {
+class DefaultProxyResolverFactory : public ProxyResolverFactoryV8Tracing {
  public:
   DefaultProxyResolverFactory(
       HostResolver* host_resolver,
       const ProxyResolver::LoadStateChangedCallback& callback)
-      : LegacyProxyResolverFactory(true),
-        host_resolver_(host_resolver),
-        callback_(callback) {}
+      : ProxyResolverFactoryV8Tracing(host_resolver, nullptr, callback) {}
 
-  scoped_ptr<ProxyResolver> CreateProxyResolver() override {
-    return make_scoped_ptr(new ProxyResolverV8Tracing(host_resolver_, nullptr,
-                                                      nullptr, callback_));
+  // ProxyResolverFactoryV8Tracing override.
+  scoped_ptr<ProxyResolverErrorObserver> CreateErrorObserver() override {
+    return nullptr;
   }
-
- private:
-  HostResolver* const host_resolver_;
-  const ProxyResolver::LoadStateChangedCallback callback_;
 };
 
 scoped_ptr<ProxyResolverFactory> CreateDefaultProxyResolver(