Add initial Controller to DownloadService

components/download/internal/model_impl.h

Index: components/download/internal/model_impl.h
diff --git a/components/download/internal/model_impl.h b/components/download/internal/model_impl.h
index 3f4d198d039720b9167c46635f6ff41ce101f9bf..bb5fecb15f3af647bb103011752e7effe7f13424 100644
--- a/components/download/internal/model_impl.h
+++ b/components/download/internal/model_impl.h
@@ -23,11 +23,11 @@ struct Entry;
 // The internal implementation of Model.
 class ModelImpl : public Model {
  public:
-  ModelImpl(Client* client, std::unique_ptr<Store> store);
+  ModelImpl(std::unique_ptr<Store> store);
   ~ModelImpl() override;
 
   // Model implementation.
-  void Initialize() override;
+  void Initialize(Client* client) override;
   void Add(const Entry& entry) override;
   void Update(const Entry& entry) override;
   void Remove(const std::string& guid) override;
@@ -51,7 +51,7 @@ class ModelImpl : public Model {
 
   // The external Model::Client reference that will receive all interesting
   // Model notifications.
-  Client* const client_;
+  Client* client_;
 
   // The backing Store that is responsible for saving and loading the
   // persisted entries.