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

services/preferences/public/cpp/tests/pref_store_client_unittest.cc

Index: services/preferences/public/cpp/tests/pref_store_client_unittest.cc
diff --git a/services/preferences/public/cpp/tests/pref_store_client_unittest.cc b/services/preferences/public/cpp/tests/pref_store_client_unittest.cc
index dbf86d41650d6a7ab3255e6567dc9738dfa4583a..05ee91b401032ca13692ac8b8afa420dc7059485 100644
--- a/services/preferences/public/cpp/tests/pref_store_client_unittest.cc
+++ b/services/preferences/public/cpp/tests/pref_store_client_unittest.cc
@@ -41,7 +41,7 @@ class PrefStoreClientTest : public testing::Test {
   bool initialized() { return store_->IsInitializationComplete(); }
   void OnPrefChanged(const std::string& key, const base::Value& value) {
     std::vector<mojom::PrefUpdatePtr> updates;
-    updates.push_back(mojom::PrefUpdate::New(key, value.CreateDeepCopy(), 0));
+    updates.push_back(mojom::PrefUpdate::New(key, value, 0));
     observer_ptr_->OnPrefsChanged(std::move(updates));
   }
   void OnInitializationCompleted() {
@@ -51,8 +51,7 @@ class PrefStoreClientTest : public testing::Test {
   // testing::Test:
   void SetUp() override {
     store_ = new PrefStoreClient(mojom::PrefStoreConnection::New(
-        mojo::MakeRequest(&observer_ptr_),
-        base::MakeUnique<base::DictionaryValue>(), false));
+        mojo::MakeRequest(&observer_ptr_), base::DictionaryValue(), false));
     store_->AddObserver(&observer_);
   }
   void TearDown() override {
@@ -170,7 +169,7 @@ TEST_F(PrefStoreClientTest, Initialized) {
   prefs->Set(key, pref.CreateDeepCopy());
   auto store =
       make_scoped_refptr(new PrefStoreClient(mojom::PrefStoreConnection::New(
-          mojo::MakeRequest(&observer_ptr), std::move(prefs), true)));
+          mojo::MakeRequest(&observer_ptr), *prefs, true)));
   store->AddObserver(&observer);
 
   const base::Value* value = nullptr;