Switch base::Value typemapping to be by value instead of by unique_ptr.

services/preferences/pref_store_manager_impl.cc

 // Copyright 2017 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 "services/preferences/pref_store_manager_impl.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/memory/ref_counted.h"
@@ skipping 230 matching lines @@
     const ConnectCallback& callback) {
   std::vector<std::string> observed_prefs;
   for (auto& registration : pref_registry->registrations) {
     observed_prefs.push_back(registration.first);
     const auto& key = registration.first;
     auto& default_value = registration.second->default_value;
     const base::Value* old_default = nullptr;
     // TODO(sammc): Once non-owning registrations are supported, disallow
     // multiple owners instead of just checking for consistent defaults.
     if (defaults_->GetValue(key, &old_default))
-      DCHECK(old_default->Equals(default_value.get()));
+      DCHECK_EQ(*old_default, default_value);
     else
-      defaults_->SetDefaultValue(key, std::move(default_value));
+      defaults_->SetDefaultValue(key, default_value.CreateDeepCopy());
   }
 
   // Only connect to pref stores the client isn't already connected to.
   PrefStorePtrs ptrs;
   for (const auto& entry : pref_store_ptrs_) {
     if (!base::ContainsValue(already_connected_types, entry.first)) {
       ptrs.insert(std::make_pair(entry.first, entry.second.get()));
     }
   }
   ConnectionBarrier::Create(
       ptrs,
       persistent_pref_store_->CreateConnection(
           PersistentPrefStoreImpl::ObservedPrefs(observed_prefs.begin(),
                                                  observed_prefs.end())),
       observed_prefs, callback);
 }
 
 void PrefStoreManagerImpl::OnPersistentPrefStoreReady() {
   DVLOG(1) << "PersistentPrefStore ready";
   if (AllConnected()) {
     ProcessPendingConnects();
   }
 }
 
 }  // namespace prefs