Add a URL param to indicate group selection in Instant field trial.

chrome/browser/search_engines/template_url.h

Index: chrome/browser/search_engines/template_url.h
diff --git a/chrome/browser/search_engines/template_url.h b/chrome/browser/search_engines/template_url.h
index a723530c00f0d13210ad1c9f1ffdcc6a1ce2050b..36e210458000368e1be89af07122e19466500064 100644
--- a/chrome/browser/search_engines/template_url.h
+++ b/chrome/browser/search_engines/template_url.h
@@ -16,6 +16,7 @@
 #include "googleurl/src/gurl.h"
 
 class PrefService;
+class Profile;
 class SearchTermsData;
 class TemplateURL;
 class WebDataService;
@@ -71,6 +72,7 @@ class TemplateURLRef {
   //
   // The TemplateURL is used to determine the input encoding for the term.
   std::string ReplaceSearchTerms(
+      Profile* profile,
       const TemplateURL& host,
       const string16& terms,
       int accepted_suggestion,
@@ -158,6 +160,7 @@ class TemplateURLRef {
     GOOGLE_ACCEPTED_SUGGESTION,
     GOOGLE_BASE_URL,
     GOOGLE_BASE_SUGGEST_URL,
+    GOOGLE_INSTANT_FIELD_TRIAL_GROUP,
     GOOGLE_ORIGINAL_QUERY_FOR_SUGGESTION,
     GOOGLE_RLZ,
     GOOGLE_SEARCH_FIELDTRIAL_GROUP,