Putting histogram names of tracked prefs in tracked_preference_histogram_name file.

components/user_prefs/tracked/tracked_preference_helper.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 "components/user_prefs/tracked/tracked_preference_helper.h"
 
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
+#include "components/user_prefs/tracked/tracked_preference_histogram_names.h"
 
 TrackedPreferenceHelper::TrackedPreferenceHelper(
     const std::string& pref_path,
     size_t reporting_id,
     size_t reporting_ids_count,
     PrefHashFilter::EnforcementLevel enforcement_level,
     PrefHashFilter::ValueType value_type)
     : pref_path_(pref_path),
       reporting_id_(reporting_id),
       reporting_ids_count_(reporting_ids_count),
       enforce_(enforcement_level == PrefHashFilter::ENFORCE_ON_LOAD),
       personal_(value_type == PrefHashFilter::VALUE_PERSONAL) {
 }
 
 TrackedPreferenceHelper::ResetAction TrackedPreferenceHelper::GetAction(
     PrefHashStoreTransaction::ValueState value_state) const {
   switch (value_state) {
-    case PrefHashStoreTransaction::UNCHANGED:
-      // Desired case, nothing to do.
-      return DONT_RESET;
-    case PrefHashStoreTransaction::CLEARED:
-      // Unfortunate case, but there is nothing we can do.
-      return DONT_RESET;
+    case PrefHashStoreTransaction::UNCHANGED:  // Desired case, nothing to do.
+    case PrefHashStoreTransaction::CLEARED:  // Unfortunate case, nothing to do.
     case PrefHashStoreTransaction::TRUSTED_NULL_VALUE:  // Falls through.
-    case PrefHashStoreTransaction::TRUSTED_UNKNOWN_VALUE:
-      // It is okay to seed the hash in this case.
-      return DONT_RESET;

[gab, 2015/12/14 19:29:27]

I preferred this format as it groups things that are the same thing (i.e. some
ValueState map to the same ResetAction but for different reasons, splitting them
here I think helped readability).

Pretty sure this doesn't impact performance and IMO it helps readability so I'd
say keep it.

[Deepak, 2015/12/15 04:39:36]

Done.

+    case PrefHashStoreTransaction::TRUSTED_UNKNOWN_VALUE:  // Seed the hash.
     case PrefHashStoreTransaction::SECURE_LEGACY:
       // Accept secure legacy device ID based hashes.
       return DONT_RESET;
     case PrefHashStoreTransaction::UNTRUSTED_UNKNOWN_VALUE:  // Falls through.
     case PrefHashStoreTransaction::CHANGED:
       return enforce_ ? DO_RESET : WANTED_RESET;
   }
   NOTREACHED() << "Unexpected PrefHashStoreTransaction::ValueState: "
                << value_state;
   return DONT_RESET;
 }
 
 bool TrackedPreferenceHelper::IsPersonal() const {
   return personal_;
 }
 
 void TrackedPreferenceHelper::ReportValidationResult(
     PrefHashStoreTransaction::ValueState value_state) const {
   switch (value_state) {
     case PrefHashStoreTransaction::UNCHANGED:
-      UMA_HISTOGRAM_ENUMERATION("Settings.TrackedPreferenceUnchanged",
-                                reporting_id_, reporting_ids_count_);
+      UMA_HISTOGRAM_ENUMERATION(
+          user_prefs::tracked::kTrackedPrefHistogramUnchanged, reporting_id_,
+          reporting_ids_count_);
       return;
     case PrefHashStoreTransaction::CLEARED:
-      UMA_HISTOGRAM_ENUMERATION("Settings.TrackedPreferenceCleared",
-                                reporting_id_, reporting_ids_count_);
+      UMA_HISTOGRAM_ENUMERATION(
+          user_prefs::tracked::kTrackedPrefHistogramCleared, reporting_id_,
+          reporting_ids_count_);
       return;
     case PrefHashStoreTransaction::SECURE_LEGACY:
       UMA_HISTOGRAM_ENUMERATION(
-          "Settings.TrackedPreferenceMigratedLegacyDeviceId", reporting_id_,
+          user_prefs::tracked::kTrackedPrefHistogramMigratedLegacyDeviceId,
+          reporting_id_, reporting_ids_count_);
+      return;
+    case PrefHashStoreTransaction::CHANGED:
+      UMA_HISTOGRAM_ENUMERATION(
+          user_prefs::tracked::kTrackedPrefHistogramChanged, reporting_id_,
           reporting_ids_count_);
       return;
-    case PrefHashStoreTransaction::CHANGED:
-      UMA_HISTOGRAM_ENUMERATION("Settings.TrackedPreferenceChanged",
-                                reporting_id_, reporting_ids_count_);
-      return;
     case PrefHashStoreTransaction::UNTRUSTED_UNKNOWN_VALUE:
-      UMA_HISTOGRAM_ENUMERATION("Settings.TrackedPreferenceInitialized",
-                                reporting_id_, reporting_ids_count_);
+      UMA_HISTOGRAM_ENUMERATION(
+          user_prefs::tracked::kTrackedPrefHistogramInitialized, reporting_id_,
+          reporting_ids_count_);
       return;
     case PrefHashStoreTransaction::TRUSTED_UNKNOWN_VALUE:
-      UMA_HISTOGRAM_ENUMERATION("Settings.TrackedPreferenceTrustedInitialized",
-                                reporting_id_, reporting_ids_count_);
+      UMA_HISTOGRAM_ENUMERATION(
+          user_prefs::tracked::kTrackedPrefHistogramTrustedInitialized,
+          reporting_id_, reporting_ids_count_);
       return;
     case PrefHashStoreTransaction::TRUSTED_NULL_VALUE:
-      UMA_HISTOGRAM_ENUMERATION("Settings.TrackedPreferenceNullInitialized",
-                                reporting_id_, reporting_ids_count_);
+      UMA_HISTOGRAM_ENUMERATION(
+          user_prefs::tracked::kTrackedPrefHistogramNullInitialized,
+          reporting_id_, reporting_ids_count_);
       return;
   }
   NOTREACHED() << "Unexpected PrefHashStoreTransaction::ValueState: "
                << value_state;
 }
 
 void TrackedPreferenceHelper::ReportAction(ResetAction reset_action) const {
   switch (reset_action) {
     case DONT_RESET:
       // No report for DONT_RESET.
       break;
     case WANTED_RESET:
-      UMA_HISTOGRAM_ENUMERATION("Settings.TrackedPreferenceWantedReset",
-                                reporting_id_, reporting_ids_count_);
+      UMA_HISTOGRAM_ENUMERATION(
+          user_prefs::tracked::kTrackedPrefHistogramWantedReset, reporting_id_,
+          reporting_ids_count_);
       break;
     case DO_RESET:
-      UMA_HISTOGRAM_ENUMERATION("Settings.TrackedPreferenceReset",
+      UMA_HISTOGRAM_ENUMERATION(user_prefs::tracked::kTrackedPrefHistogramReset,
                                 reporting_id_, reporting_ids_count_);
       break;
   }
 }
 
 void TrackedPreferenceHelper::ReportSplitPreferenceChangedCount(
     size_t count) const {
   // The histogram below is an expansion of the UMA_HISTOGRAM_COUNTS_100 macro
   // adapted to allow for a dynamically suffixed histogram name.
   // Note: The factory creates and owns the histogram.
-  base::HistogramBase* histogram =
-      base::LinearHistogram::FactoryGet(
-          "Settings.TrackedSplitPreferenceChanged." + pref_path_,
-          1,
-          100,  // Allow counts up to 100.
-          101,
-          base::HistogramBase::kUmaTargetedHistogramFlag);
+  base::HistogramBase* histogram = base::LinearHistogram::FactoryGet(
+      user_prefs::tracked::kTrackedSplitPrefHistogramChanged + pref_path_, 1,
+      100,  // Allow counts up to 100.
+      101, base::HistogramBase::kUmaTargetedHistogramFlag);
   histogram->Add(count);
 }