Improve performance of proxy resolver by tracing DNS dependencies.

net/proxy/proxy_resolver_error_observer.h

Index: net/proxy/proxy_resolver_error_observer.h
diff --git a/net/proxy/proxy_resolver_error_observer.h b/net/proxy/proxy_resolver_error_observer.h
index 9176c2f233fb579a80aece21b211898232decee5..0002325b47d481f21975ad9b3fa2c126293f7897 100644
--- a/net/proxy/proxy_resolver_error_observer.h
+++ b/net/proxy/proxy_resolver_error_observer.h
@@ -11,10 +11,7 @@
 
 namespace net {
 
-// Interface for observing JavaScript error messages from PAC scripts. The
-// default implementation of the ProxyResolverJSBindings takes a class
-// implementing this interface and forwards all JavaScript errors related to
-// PAC scripts.
+// Interface for observing JavaScript error messages from PAC scripts.

[mmenke, 2013/01/29 20:19:08]

May want to mention that this can be called on any thread.

[eroman, 2013/01/29 22:51:23]

Done.

It is ambiguous what thread this will be called on, since this interface isn't
tied to any particular implementation (for instance if used from the
multithreaded proxy resolver it could be any of the workers).

I have added a generic comment.

 class NET_EXPORT_PRIVATE ProxyResolverErrorObserver {
  public:
   ProxyResolverErrorObserver() {}