Adds InstantExtendedEnabledParam to the search request URL iff the query extraction flag is enabled.

chrome/browser/search/search.h

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_SEARCH_SEARCH_H_
 #define CHROME_BROWSER_SEARCH_SEARCH_H_
 
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 53 matching lines @@
 bool IsInstantExtendedAPIEnabled();
 
 // Returns whether the suggest is enabled for the given |profile|.
 bool IsSuggestPrefEnabled(Profile* profile);
 
 // Returns the value to pass to the &espv CGI parameter when loading the
 // embedded search page from the user's default search provider. Returns 0 if
 // the Instant Extended API is not enabled.
 uint64 EmbeddedSearchPageVersion();
 
+// Returns a string indicating whether InstantExtended is enabled, suitable
+// for adding as a query string param to the homepage or search requests.
+//
+// On desktop, |for_search| is set to true for search requests and this
+// function returns an empty string when the query extraction is disabled.
+// On mobile, |for_search| param is unused because the query extraction is

[samarth, 2014/02/04 17:17:05]

This is confusing. Why isn't |for_search| set correctly on mobile?  Looking at
the callsites, I think toolbar_model_android.cc should be setting |for_search|
to true.

[kmadhusu, 2014/02/04 17:49:59]

I am not sure about the callers of that function. That's why I passed false to
be on the safer side. Adding yusufo@ to review toolbar_model_android.cc changes.

[kmadhusu, 2014/02/04 19:39:54]

Fixed.

+// always enabled.
+std::string InstantExtendedEnabledParam(bool for_search);
+
 // Returns whether query extraction is enabled.
 bool IsQueryExtractionEnabled();
 
 // Extracts and returns search terms from |url|. Returns empty string if the URL
 // is not secure or doesn't have a search term replacement key.  Does not
 // consider IsQueryExtractionEnabled() and Instant support state of the page and
 // does not check for a privileged process, so most callers should use
 // GetSearchTerms() below instead.
 base::string16 GetSearchTermsFromURL(Profile* profile, const GURL& url);
 
@@ skipping 168 matching lines @@
 bool GetBoolValueForFlagWithDefault(const std::string& flag,
                                     bool default_value,
                                     const FieldTrialFlags& flags);
 
 // Returns the Cacheable New Tab Page URL for the given |profile|.
 GURL GetNewTabPageURL(Profile* profile);
 
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_SEARCH_SEARCH_H_