[omnibox] Added 'OmniboxTailSuggestions' flag

components/omnibox/browser/omnibox_field_trial.h

 // Copyright 2014 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 COMPONENTS_OMNIBOX_BROWSER_OMNIBOX_FIELD_TRIAL_H_
 #define COMPONENTS_OMNIBOX_BROWSER_OMNIBOX_FIELD_TRIAL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "components/metrics/proto/omnibox_event.pb.h"
 #include "components/omnibox/browser/autocomplete_input.h"
 #include "components/omnibox/browser/autocomplete_match_type.h"
 
 namespace base {
 struct Feature;
 class TimeDelta;
 }
 
 namespace omnibox {
 
 extern const base::Feature kNewOmniboxAnswerTypes;
 extern const base::Feature kOmniboxEntitySuggestions;
+extern const base::Feature kOmniboxTailSuggestions;
 extern const base::Feature kEnableClipboardProvider;
 extern const base::Feature kSearchProviderWarmUpOnFocus;
 extern const base::Feature kSearchProviderContextAllowHttpsUrls;
 extern const base::Feature kZeroSuggestRedirectToChrome;
 extern const base::Feature kZeroSuggestSwapTitleAndUrl;
 extern const base::Feature kDisplayTitleForCurrentUrl;
 extern const base::Feature kUIExperimentMaxAutocompleteMatches;
 extern const base::Feature kUIExperimentVerticalLayout;
 extern const base::Feature kUIExperimentVerticalMargin;
 }
@@ skipping 501 matching lines @@
   // prioritize different wildcard contexts, see the implementation.  How to
   // interpret the value is left to the caller; this is rule-dependent.
   static std::string GetValueForRuleInContext(
       const std::string& rule,
       metrics::OmniboxEventProto::PageClassification page_classification);
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(OmniboxFieldTrial);
 };
 
 #endif  // COMPONENTS_OMNIBOX_BROWSER_OMNIBOX_FIELD_TRIAL_H_