Divide CookieStoreIOS into two different classes with different backends

components/cronet/ios/cronet_environment.mm

Index: components/cronet/ios/cronet_environment.mm
diff --git a/components/cronet/ios/cronet_environment.mm b/components/cronet/ios/cronet_environment.mm
index f8f794acf7e71b2f003290d269c50f32323beb1c..68d09a3d28da3681e0a6a27767f3f54b80142415 100644
--- a/components/cronet/ios/cronet_environment.mm
+++ b/components/cronet/ios/cronet_environment.mm
@@ -311,9 +311,9 @@ void CronetEnvironment::InitializeOnNetworkThread() {
 
   context_builder.set_host_resolver(std::move(mapped_host_resolver));
 
-  std::unique_ptr<net::CookieStore> cookie_store(
-      net::CookieStoreIOS::CreateCookieStore(
-          [NSHTTPCookieStorage sharedHTTPCookieStorage]));
+  std::unique_ptr<net::CookieStore> cookie_store =
+      base::MakeUnique<CookieStoreIOS>(
+          [NSHTTPCookieStorage sharedHTTPCookieStorage]);
   context_builder.SetCookieAndChannelIdStores(std::move(cookie_store), nullptr);
 
   std::unordered_set<std::string> quic_host_whitelist;