Use std::string instead of mojo::String in //net.

chrome/browser/net/utility_process_mojo_proxy_resolver_factory.h

Index: chrome/browser/net/utility_process_mojo_proxy_resolver_factory.h
diff --git a/chrome/browser/net/utility_process_mojo_proxy_resolver_factory.h b/chrome/browser/net/utility_process_mojo_proxy_resolver_factory.h
index 392b82bd809db7a7523b59b093e62a4687f9614a..b39362372e789d3cfacb9ffa7d774ff7071934ca 100644
--- a/chrome/browser/net/utility_process_mojo_proxy_resolver_factory.h
+++ b/chrome/browser/net/utility_process_mojo_proxy_resolver_factory.h
@@ -32,7 +32,7 @@ class UtilityProcessMojoProxyResolverFactory
 
   // Overridden from net::MojoProxyResolverFactory:
   std::unique_ptr<base::ScopedClosureRunner> CreateResolver(
-      const mojo::String& pac_script,
+      const std::string& pac_script,
       mojo::InterfaceRequest<net::interfaces::ProxyResolver> req,
       net::interfaces::ProxyResolverFactoryRequestClientPtr client) override;