[Android NTP] Logging histograms for users that are part of a control group.

chrome/browser/search/suggestions/suggestions_service.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 CHROME_BROWSER_SEARCH_SUGGESTIONS_SUGGESTIONS_SERVICE_H_
 #define CHROME_BROWSER_SEARCH_SUGGESTIONS_SUGGESTIONS_SERVICE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 19 matching lines @@
 
 namespace suggestions {
 
 class SuggestionsStore;
 
 extern const char kSuggestionsFieldTrialName[];
 extern const char kSuggestionsFieldTrialURLParam[];
 extern const char kSuggestionsFieldTrialSuggestionsSuffixParam[];
 extern const char kSuggestionsFieldTrialBlacklistSuffixParam[];
 extern const char kSuggestionsFieldTrialStateParam[];
+extern const char kSuggestionsFieldTrialControlParam[];
 extern const char kSuggestionsFieldTrialStateEnabled[];
 
 // An interface to fetch server suggestions asynchronously.
 class SuggestionsService : public KeyedService, public net::URLFetcherDelegate {
  public:
   typedef base::Callback<void(const SuggestionsProfile&)> ResponseCallback;
 
   SuggestionsService(Profile* profile,
                      scoped_ptr<SuggestionsStore> suggestions_store);
   virtual ~SuggestionsService();
 
   // Whether this service is enabled.
   static bool IsEnabled();
 
+  // Whether the user is part of a control group.
+  static bool IsControlGroup();
+
   // Request suggestions data, which will be passed to |callback|. Initiates a
   // fetch request unless a pending one exists. To prevent multiple requests,
   // we place all |callback|s in a queue and update them simultaneously when
   // fetch request completes. Also posts a task to execute OnRequestTimeout
   // if the request hasn't completed in a given amount of time.
   void FetchSuggestionsData(ResponseCallback callback);
 
   // Similar to FetchSuggestionsData but doesn't post a task to execute
   // OnDelaySinceFetch.
   void FetchSuggestionsDataNoTimeout(ResponseCallback callback);
@@ skipping 70 matching lines @@
   // Timeout (in ms) before serving requestors after a fetch suggestions request
   // has been issued.
   int request_timeout_ms_;
 
   DISALLOW_COPY_AND_ASSIGN(SuggestionsService);
 };
 
 }  // namespace suggestions
 
 #endif  // CHROME_BROWSER_SEARCH_SUGGESTIONS_SUGGESTIONS_SERVICE_H_