Improve performance of proxy resolver by tracing DNS dependencies.

net/data/proxy_resolver_v8_tracing_unittest/dns.js

Index: net/data/proxy_resolver_v8_tracing_unittest/dns.js
diff --git a/net/data/proxy_resolver_v8_tracing_unittest/dns.js b/net/data/proxy_resolver_v8_tracing_unittest/dns.js
new file mode 100644
index 0000000000000000000000000000000000000000..80fd4b7a2f940508a63498000d55a94815f392dc
--- /dev/null
+++ b/net/data/proxy_resolver_v8_tracing_unittest/dns.js
@@ -0,0 +1,27 @@
+var g_iteration = 0;
+
+function FindProxyForURL(url, host) {
+  alert('iteration: ' + g_iteration++);
+
+  var ips = [
+    myIpAddress(),
+    dnsResolve(''),
+    dnsResolve('host1'),
+    dnsResolve('host2'),
+    dnsResolve('host3'),
+    myIpAddress(),
+    dnsResolve('host3'),
+    dnsResolve('host1'),
+    myIpAddress(),
+    dnsResolve('host2'),
+    dnsResolve('host4'),
+  ];
+
+  for (var i = 0; i < ips.length; ++i) {
+    // Stringize everything.
+    ips[i] = '' + ips[i];
+  }
+
+  var proxyHost = ips.join('-');
+  return "PROXY " + proxyHost + ":99";
+}