Omnibox UI Experiments: Add flag to change max autocomplete matches.

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>
 
@@ skipping 14 matching lines @@
 namespace omnibox {
 
 extern const base::Feature kNewOmniboxAnswerTypes;
 extern const base::Feature kOmniboxEntitySuggestions;
 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 kUIExperimentVerticalMargin;
 }
 
 // The set of parameters customizing the HUP scoring.
 struct HUPScoringParams {
   // A set of parameters describing how to cap a given count score.  First,
   // we apply a half-life based decay of the given count and then find the
   // maximum relevance score based on the decay factor or counts specified
   // in the corresponding bucket list. See comment on |buckets_| for details.
   class ScoreBuckets {
@@ skipping 445 matching lines @@
   // Parameter names used by the Physical Web experimental scoring experiments.
   static const char kPhysicalWebZeroSuggestBaseRelevanceParam[];
   static const char kPhysicalWebAfterTypingBaseRelevanceParam[];
 
   // Parameter names used by the experiment redirecting Zero Suggestion requests
   // to a service provided by the Chrome team.
   static const char kZeroSuggestRedirectToChromeServerAddressParam[];
   static const char kZeroSuggestRedirectToChromeAdditionalFieldsParam[];
 
   // Parameter names used by UI experiments.
+  static const char kUIMaxAutocompleteMatchesParam[];
   static const char kUIVerticalMarginParam[];
 
   // The amount of time to wait before sending a new suggest request after the
   // previous one unless overridden by a field trial parameter.
   // Non-const because some unittests modify this value.
   static int kDefaultMinimumTimeBetweenSuggestQueriesMs;
 
  private:
   friend class OmniboxFieldTrialTest;
 
@@ skipping 13 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_