Don't set ion=1 for hidden Instant modes.

chrome/browser/search_engines/search_terms_data.h

 // Copyright (c) 2011 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_ENGINES_SEARCH_TERMS_DATA_H_
 #define CHROME_BROWSER_SEARCH_ENGINES_SEARCH_TERMS_DATA_H_
 #pragma once
 
 #include <string>
 
@@ skipping 17 matching lines @@
   virtual std::string GoogleBaseURLValue() const = 0;
 
   // Returns the locale used by the application.
   virtual std::string GetApplicationLocale() const = 0;
 
 #if defined(OS_WIN) && defined(GOOGLE_CHROME_BUILD)
   // Returns the value for the Chrome Omnibox rlz.
   virtual string16 GetRlzParameterValue() const = 0;
 #endif
 
+  // Returns a string indicating whether Instant (in the visible-preview mode)
+  // is enabled, suitable for adding as a query string param to the homepage
+  // (instant_url) request. Returns an empty string if Instant is disabled,
+  // or if it's only active in a hidden field trial mode. Determining this
+  // requires accessing the Profile, so this can only ever be non-empty for
+  // UIThreadSearchTermsData.
+  virtual std::string InstantEnabledParam() const;
+
   // Returns a string indicating the Instant field trial group, suitable for
   // adding as a query string param to suggest/search URLs, or an empty string
   // if the field trial is not active. Checking the field trial group requires
   // accessing the Profile, which means this can only ever be non-empty for
   // UIThreadSearchTermsData.
   virtual std::string InstantFieldTrialUrlParam() const;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SearchTermsData);
 };
 
 // Implementation of SearchTermsData that is only usable on the UI thread.
 class UIThreadSearchTermsData : public SearchTermsData {
  public:
   UIThreadSearchTermsData();
 
-  // Callers who need an accurate answer from InstantFieldTrialUrlParam() must
-  // set the profile here before calling that.
+  // Callers who need an accurate answer from InstantFieldTrialUrlParam() or
+  // InstantEnabledParam() must set the profile here before calling them.
   void set_profile(Profile* profile) { profile_ = profile; }
 
   // Implementation of SearchTermsData.
   virtual std::string GoogleBaseURLValue() const OVERRIDE;
   virtual std::string GetApplicationLocale() const OVERRIDE;
 #if defined(OS_WIN) && defined(GOOGLE_CHROME_BUILD)
   virtual string16 GetRlzParameterValue() const OVERRIDE;
 #endif
 
   // This returns the empty string unless set_profile() has been called with a
   // non-NULL Profile.
+  virtual std::string InstantEnabledParam() const OVERRIDE;
+
+  // This returns the empty string unless set_profile() has been called with a
+  // non-NULL Profile.
   virtual std::string InstantFieldTrialUrlParam() const OVERRIDE;
 
   // Used by tests to set the value for the Google base url. This takes
   // ownership of the given std::string.
   static void SetGoogleBaseURL(std::string* google_base_url);
 
  private:
   static std::string* google_base_url_;
   Profile* profile_;
 
   DISALLOW_COPY_AND_ASSIGN(UIThreadSearchTermsData);
 };
 
 #endif  // CHROME_BROWSER_SEARCH_ENGINES_SEARCH_TERMS_DATA_H_