Improve performance of proxy resolver by tracing DNS dependencies.

net/data/proxy_resolver_v8_tracing_unittest/too_many_alerts.js

Index: net/data/proxy_resolver_v8_tracing_unittest/too_many_alerts.js
diff --git a/net/data/proxy_resolver_v8_tracing_unittest/too_many_alerts.js b/net/data/proxy_resolver_v8_tracing_unittest/too_many_alerts.js
new file mode 100644
index 0000000000000000000000000000000000000000..762fd57c76f0b37b77eab912aa5b501eca2f89a6
--- /dev/null
+++ b/net/data/proxy_resolver_v8_tracing_unittest/too_many_alerts.js
@@ -0,0 +1,9 @@
+function FindProxyForURL(url, host) {
+  dnsResolve(host);
+
+  for (var i = 0; i < 50; i++) {
+    alert('Gee, all these alerts are silly!');
+  }
+
+  return "PROXY foo:99";
+}