Add a field trial to disable deferred committing of cookie changes

chrome/browser/prerender/prerender_field_trial.cc

Index: chrome/browser/prerender/prerender_field_trial.cc
===================================================================
--- chrome/browser/prerender/prerender_field_trial.cc	(revision 272804)
+++ chrome/browser/prerender/prerender_field_trial.cc	(working copy)
@@ -75,6 +75,7 @@
     "SkipPrerenderServiceCandidates";
 const char kDisableSessionStorageNamespaceMerging[] =
     "DisableSessionStorageNamespaceMerging";
+const char kPrerenderCookieStore[] = "PrerenderCookieStore";
 
 void SetupPrerenderFieldTrial() {
   const FieldTrial::Probability divisor = 1000;
@@ -434,4 +435,9 @@
       kDisabledGroup;
 }
 
+bool IsPrerenderCookieStoreEnabled() {
+  return GetLocalPredictorSpecValue(kPrerenderCookieStore) != kDisabledGroup &&
+      FieldTrialList::FindFullName(kPrerenderCookieStore) != kDisabledGroup;
+}
+
 }  // namespace prerender