Adds a field trial flag to control whether to use an alternate Instant search base page URL for pre…

chrome/browser/search/search.h

Index: chrome/browser/search/search.h
diff --git a/chrome/browser/search/search.h b/chrome/browser/search/search.h
index 75c4aeb5a25f98a06f72b60957fe475b6f7b5668..842b03748183aca882545b9689e1a7e0fbc07126 100644
--- a/chrome/browser/search/search.h
+++ b/chrome/browser/search/search.h
@@ -284,6 +284,11 @@ bool GetBoolValueForFlagWithDefault(const std::string& flag,
 // Returns the Cacheable New Tab Page URL for the given |profile|.
 GURL GetNewTabPageURL(Profile* profile);
 
+// Returns true if 'use_alternate_instant_url' flag is set to true in field
+// trials to use an alternate Instant search base page URL for prefetching
+// search results. This allows experimentation of Instant search.
+bool ShouldUseAltInstantURL();
+
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_SEARCH_SEARCH_H_