Resetting metrics ids on clump detection.

chrome/browser/metrics/cloned_install_detector.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/metrics/cloned_install_detector.h"
 
 #include "base/bind.h"
 #include "base/metrics/histogram.h"
 #include "base/prefs/pref_registry_simple.h"
 #include "base/prefs/pref_service.h"
@@ skipping 54 matching lines @@
   if (raw_id.empty()) {
     LogMachineIdState(ID_GENERATION_FAILED);
     local_state->ClearPref(prefs::kMetricsMachineId);
     return;
   }
 
   int hashed_id = HashRawId(raw_id);
 
   MachineIdState id_state = ID_NO_STORED_VALUE;
   if (local_state->HasPrefPath(prefs::kMetricsMachineId)) {
-    id_state = local_state->GetInteger(prefs::kMetricsMachineId) == hashed_id ?
-        ID_UNCHANGED : ID_CHANGED;
+    if (local_state->GetInteger(prefs::kMetricsMachineId) != hashed_id) {
+      id_state = ID_CHANGED;
+      // TODO(jwd): Use a callback to set the reset pref. That way
+      // ClonedInstallDetector doesn't need to know about this pref.
+      local_state->SetBoolean(prefs::kMetricsResetIds, true);
+    } else {
+      id_state = ID_UNCHANGED;
+    }
   }
 
   LogMachineIdState(id_state);
 
   local_state->SetInteger(prefs::kMetricsMachineId, hashed_id);
 }
 
 // static
 void ClonedInstallDetector::RegisterPrefs(PrefRegistrySimple* registry) {
   registry->RegisterIntegerPref(prefs::kMetricsMachineId, 0);
 }
 
 }  // namespace metrics