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

chrome/browser/search/suggestions/suggestions_service.cc

 // 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.
 
 #include "chrome/browser/search/suggestions/suggestions_service.h"
 
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/sparse_histogram.h"
@@ skipping 61 matching lines @@
 const int kDefaultRequestTimeoutMs = 200;
 
 }  // namespace
 
 const char kSuggestionsFieldTrialName[] = "ChromeSuggestions";
 const char kSuggestionsFieldTrialURLParam[] = "url";
 const char kSuggestionsFieldTrialSuggestionsSuffixParam[] =
     "suggestions_suffix";
 const char kSuggestionsFieldTrialBlacklistSuffixParam[] = "blacklist_suffix";
 const char kSuggestionsFieldTrialStateParam[] = "state";
+const char kSuggestionsFieldTrialControlParam[] = "control";
 const char kSuggestionsFieldTrialStateEnabled[] = "enabled";
 const char kSuggestionsFieldTrialTimeoutMs[] = "timeout_ms";
 
 SuggestionsService::SuggestionsService(
     Profile* profile, scoped_ptr<SuggestionsStore> suggestions_store)
     : suggestions_store_(suggestions_store.Pass()),
       thumbnail_manager_(new ThumbnailManager(profile)),
       profile_(profile),
       weak_ptr_factory_(this),
       request_timeout_ms_(kDefaultRequestTimeoutMs) {
@@ skipping 12 matching lines @@
 }
 
 SuggestionsService::~SuggestionsService() {}
 
 // static
 bool SuggestionsService::IsEnabled() {
   return GetExperimentParam(kSuggestionsFieldTrialStateParam) ==
          kSuggestionsFieldTrialStateEnabled;
 }
 
+// static
+bool SuggestionsService::IsControlGroup() {
+  return GetExperimentParam(kSuggestionsFieldTrialControlParam) ==
+         kSuggestionsFieldTrialStateEnabled;
+}
+
 void SuggestionsService::FetchSuggestionsData(
     SuggestionsService::ResponseCallback callback) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
 
   FetchSuggestionsDataNoTimeout(callback);
 
   // Post a task to serve the cached suggestions if the request hasn't completed
   // after some time. Cancels the previous such task, if one existed.
   pending_timeout_closure_.reset(new CancelableClosure(base::Bind(
       &SuggestionsService::OnRequestTimeout, weak_ptr_factory_.GetWeakPtr())));
@@ skipping 151 matching lines @@
   return request;
 }
 
 void SuggestionsService::ServeFromCache() {
   SuggestionsProfile suggestions;
   suggestions_store_->LoadSuggestions(&suggestions);
   DispatchRequestsAndClear(suggestions, &waiting_requestors_);
 }
 
 }  // namespace suggestions