[Autofill] Dedupe profiles on each major version.

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>
@@ skipping 210 matching lines @@
 // static
 void AutofillManager::RegisterProfilePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
   registry->RegisterBooleanPref(
       prefs::kAutofillEnabled,
       true,
       user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
   registry->RegisterBooleanPref(
       prefs::kAutofillProfileUseDatesFixed, false,
       user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
+  registry->RegisterIntegerPref(
+      prefs::kAutofillLastVersionDeduped, 0,
+      user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
   // These choices are made on a per-device basis, so they're not syncable.
   registry->RegisterBooleanPref(prefs::kAutofillWalletImportEnabled, true);
   registry->RegisterBooleanPref(
       prefs::kAutofillWalletImportStorageCheckboxState, true);
 }
 
 void AutofillManager::SetExternalDelegate(AutofillExternalDelegate* delegate) {
   // TODO(jrg): consider passing delegate into the ctor.  That won't
   // work if the delegate has a pointer to the AutofillManager, but
   // future directions may not need such a pointer.
@@ skipping 1755 matching lines @@
     if (i > 0)
       fputs("Next oldest form:\n", file);
   }
   fputs("\n", file);
 
   fclose(file);
 }
 #endif  // ENABLE_FORM_DEBUG_DUMP
 
 }  // namespace autofill