Improve performance of proxy resolver by tracing DNS dependencies.

net/data/proxy_resolver_v8_tracing_unittest/global_sideffects3.js

Index: net/data/proxy_resolver_v8_tracing_unittest/global_sideffects3.js
diff --git a/net/data/proxy_resolver_v8_tracing_unittest/global_sideffects3.js b/net/data/proxy_resolver_v8_tracing_unittest/global_sideffects3.js
new file mode 100644
index 0000000000000000000000000000000000000000..04211260c3b2fcf1274727be6bf8341bafe834d8
--- /dev/null
+++ b/net/data/proxy_resolver_v8_tracing_unittest/global_sideffects3.js
@@ -0,0 +1,13 @@
+var g_iteration = 0;
+
+function FindProxyForURL(url, host) {
+  g_iteration++;
+
+  var results = [];
+  for (var i = 1; i <= g_iteration; ++i) {
+    results.push('' + dnsResolve('host' + i));
+  }
+
+  alert('iteration: ' + g_iteration);
+  return 'PROXY ' + results.join('-') + ':' + g_iteration;
+}