Componentize renderer side of DNS prefetching.

chrome/browser/net/predictor.cc

Index: chrome/browser/net/predictor.cc
diff --git a/chrome/browser/net/predictor.cc b/chrome/browser/net/predictor.cc
index 9d2a80c98afaace21cf34892d7d8201f97969da6..fb77d62913524c2e96f1fc07bd4581a727b8101a 100644
--- a/chrome/browser/net/predictor.cc
+++ b/chrome/browser/net/predictor.cc
@@ -33,6 +33,7 @@
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/pref_names.h"
 #include "components/data_reduction_proxy/core/browser/data_reduction_proxy_settings.h"
+#include "components/dns_prefetch/common/prefetch_common.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "content/public/browser/browser_thread.h"
 #include "net/base/address_list.h"
@@ -736,12 +737,23 @@ void Predictor::LearnAboutInitialNavigation(const GURL& url) {
 // includes both Page-Scan, and Link-Hover prefetching.
 // TODO(jar): Separate out link-hover prefetching, and page-scan results.
 void Predictor::DnsPrefetchList(const NameList& hostnames) {
+  if (hostnames.size() > dns_prefetch::kMaxDnsHostnamesPerRequest) {
+    LOG(DFATAL) << "Refusing to prefetch too many hostnames: "

[jar (doing other things), 2014/10/28 22:49:32]

nit: Please use DLOG.  No one will look at this... so there is no reason to
swell the binary.

It is also plausible that you should "fix" the data, by truncating any overlong
list, rather than aborting all progress.

[gunsch, 2014/10/29 23:58:29]

Covered by removing this and doing validation with a custom IpcParamTraits.

+                << hostnames.size();
+    return;
+  }
+
   // TODO(jar): Push GURL transport further back into renderer, but this will
   // require a Webkit change in the observer :-/.
   UrlList urls;
   for (NameList::const_iterator it = hostnames.begin();
        it < hostnames.end();
        ++it) {
+    if (it->length() > dns_prefetch::kMaxDnsHostnameLength) {
+      LOG(DFATAL) << "Refusing to prefetch hostname with length: "

[jar (doing other things), 2014/10/28 22:49:32]

nit: DLOG

[gunsch, 2014/10/29 23:58:29]

ditto

+                  << it->length();
+      continue;
+    }
     urls.push_back(GURL("http://" + *it + ":80"));
   }