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

components/autofill/core/browser/autofill_manager.cc

Index: components/autofill/core/browser/autofill_manager.cc
diff --git a/components/autofill/core/browser/autofill_manager.cc b/components/autofill/core/browser/autofill_manager.cc
index 49f488c2482f3962dc2a649f6eb19cdda79977c6..a21eabe8a96650e119eeaf76aeabb1c006da9e76 100644
--- a/components/autofill/core/browser/autofill_manager.cc
+++ b/components/autofill/core/browser/autofill_manager.cc
@@ -23,6 +23,7 @@
 #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"
@@ -1298,15 +1299,19 @@ int AutofillManager::GetProfilesForCreditCardUpload(
   const base::TimeDelta fifteen_minutes = base::TimeDelta::FromMinutes(15);
   int upload_decision_metrics = 0;
   bool has_profile = false;
+  bool has_modified_profile = false;
 
   // First, collect all of the addresses used recently.
   for (AutofillProfile* profile : personal_data_->GetProfiles()) {
     has_profile = true;
-    if ((now - profile->use_date()) < fifteen_minutes ||
-        (now - profile->modification_date()) < fifteen_minutes) {
+    if ((now - profile->modification_date()) < fifteen_minutes) {
+      has_modified_profile = true;
+      candidate_profiles.push_back(*profile);
+    } else if ((now - profile->use_date()) < fifteen_minutes) {
       candidate_profiles.push_back(*profile);
     }
   }
+
   if (candidate_profiles.empty()) {
     upload_decision_metrics |=
         has_profile
@@ -1389,9 +1394,14 @@ int AutofillManager::GetProfilesForCreditCardUpload(
   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;
 }