Adds TTL argument to HostCache::Set.

net/proxy/proxy_resolver_js_bindings.cc

Index: net/proxy/proxy_resolver_js_bindings.cc
diff --git a/net/proxy/proxy_resolver_js_bindings.cc b/net/proxy/proxy_resolver_js_bindings.cc
index f3f6c1558938df3ffc90319ab8404b71d5217b68..d8d02ee15a96eea587a902b08e60e9ad59b05bda 100644
--- a/net/proxy/proxy_resolver_js_bindings.cc
+++ b/net/proxy/proxy_resolver_js_bindings.cc
@@ -23,6 +23,10 @@ namespace net {
 
 namespace {
 
+// TTL for the per-request DNS cache. Applies to both successful and failed
+// DNS resolutions.
+const unsigned kCacheEntryTTLSeconds = 5 * 60;
+
 // Event parameters for a PAC error message (line number + message).
 class ErrorNetlogParams : public NetLog::EventParameters {
  public:
@@ -263,7 +267,8 @@ class DefaultJSBindings : public ProxyResolverJSBindings {
     // Save the result back to the per-request DNS cache.
     if (host_cache) {
       host_cache->Set(cache_key, result, *address_list,
-                      base::TimeTicks::Now());
+                      base::TimeTicks::Now(),
+                      base::TimeDelta::FromSeconds(kCacheEntryTTLSeconds));
     }
 
     return result;