Add options to disable each of the two aspects of the prerender service

chrome/browser/prerender/prerender_field_trial.h

Index: chrome/browser/prerender/prerender_field_trial.h
===================================================================
--- chrome/browser/prerender/prerender_field_trial.h	(revision 222044)
+++ chrome/browser/prerender/prerender_field_trial.h	(working copy)
@@ -42,6 +42,11 @@
 // provided.
 bool ShouldQueryPrerenderService(Profile* profile);
 
+// Indicates whether we should query the prerender service for the current URL
+// and candidate URLs, respectively.
+bool ShouldQueryPrerenderServiceForCurrentURL();
+bool ShouldQueryPrerenderServiceForCandidateURLs();
+
 // Returns the URL prefix to be used for the prerender service. The only thing
 // that will be appended is the urlencoded query json.
 std::string GetPrerenderServiceURLPrefix();