Adds UMA for days since previous use to help us determine the validity

components/autofill/core/browser/autofill_manager.cc

 // Copyright 2013 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 "components/autofill/core/browser/autofill_manager.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <set>
 #include <utility>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/containers/adapters.h"
 #include "base/feature_list.h"
 #include "base/files/file_util.h"
 #include "base/guid.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/path_service.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_piece.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/threading/thread_restrictions.h"
 #include "build/build_config.h"
@@ skipping 1397 matching lines @@
         }
       }
     }
   }
 
   // If none of the candidate addresses have a zip, the candidate set is
   // invalid.
   if (verified_zip.empty() && !candidate_profiles.empty())
     upload_decision_metrics |= AutofillMetrics::UPLOAD_NOT_OFFERED_NO_ZIP_CODE;
 
-  if (!upload_decision_metrics)
+  if (!upload_decision_metrics) {
     profiles->assign(candidate_profiles.begin(), candidate_profiles.end());
-
+    if (!has_modified_profile)
+      for (const AutofillProfile& profile : candidate_profiles)
+        UMA_HISTOGRAM_COUNTS_1000(
+            "Autofill.DaysSincePreviousUseAtSubmission.Profile",
+            (profile.use_date() - profile.previous_use_date()).InDays());
+  }
   return upload_decision_metrics;
 }
 
 void AutofillManager::CollectRapporSample(
     const GURL& source_url,
     const std::string& metric_name) const {
   if (source_url.is_valid() && client_->GetRapporServiceImpl()) {
     rappor::SampleDomainAndRegistryFromGURL(client_->GetRapporServiceImpl(),
                                             metric_name, source_url);
   }
@@ skipping 845 matching lines @@
 #endif  // ENABLE_FORM_DEBUG_DUMP
 
 void AutofillManager::LogCardUploadDecisions(int upload_decision_metrics) {
   AutofillMetrics::LogCardUploadDecisionMetrics(upload_decision_metrics);
   AutofillMetrics::LogCardUploadDecisionsUkm(client_->GetUkmService(),
                                              pending_upload_request_url_,
                                              upload_decision_metrics);
 }
 
 }  // namespace autofill