Pref service: Add a ScopedDictionaryPrefUpdate to track value changes.

services/preferences/public/cpp/tests/pref_store_client_unittest.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/public/cpp/pref_store_client.h"
 
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
@@ skipping 23 matching lines @@
  public:
   PrefStoreClientTest() = default;
   ~PrefStoreClientTest() override {}
 
   PrefStoreObserverMock& observer() { return observer_; }
   PrefStoreClient* store() { return store_.get(); }
 
   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, mojom::PrefUpdateValue::NewAtomicUpdate(value.CreateDeepCopy()),
+        0));
     observer_ptr_->OnPrefsChanged(std::move(updates));
   }
   void OnInitializationCompleted() {
     observer_ptr_->OnInitializationCompleted(true);
   }
 
   // testing::Test:
   void SetUp() override {
     store_ = new PrefStoreClient(mojom::PrefStoreConnection::New(
         mojo::MakeRequest(&observer_ptr_),
@@ skipping 125 matching lines @@
   EXPECT_TRUE(value->GetAsInteger(&actual_value));
   EXPECT_EQ(kValue, actual_value);
   EXPECT_CALL(observer, OnInitializationCompleted(_)).Times(0);
   EXPECT_CALL(observer, OnPrefValueChanged(_)).Times(0);
   observer_ptr.FlushForTesting();
 
   store->RemoveObserver(&observer);
 }
 
 }  // namespace prefs