Clean up Assignment Create in BlimpClientContextImpl.

blimp/client/core/context/assignment_fetcher.h

Index: blimp/client/core/context/assignment_fetcher.h
diff --git a/blimp/client/core/context/assignment_fetcher.h b/blimp/client/core/context/assignment_fetcher.h
new file mode 100644
index 0000000000000000000000000000000000000000..3818f9e9c985e7f3476f31caf6b055d52e4f62fd
--- /dev/null
+++ b/blimp/client/core/context/assignment_fetcher.h
@@ -0,0 +1,67 @@
+// Copyright 2016 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.
+
+#ifndef BLIMP_CLIENT_CORE_CONTEXT_ASSIGNMENT_FETCHER_H_
+#define BLIMP_CLIENT_CORE_CONTEXT_ASSIGNMENT_FETCHER_H_
+
+#include <memory>
+#include <string>
+
+#include "blimp/client/core/session/assignment_source.h"
+#include "blimp/client/core/session/identity_source.h"
+
+namespace blimp {
+namespace client {
+
+class AssignmentFetcher {
+ public:
+  using AuthErrorCallback = base::Callback<void(const GoogleServiceAuthError&)>;
+  using AssignmentResultCallback =
+      base::Callback<void(AssignmentRequestResult, const Assignment&)>;
+
+  AssignmentFetcher(
+      scoped_refptr<base::SingleThreadTaskRunner> io_thread_task_runner,
+      scoped_refptr<base::SingleThreadTaskRunner> file_thread_task_runner,
+      std::unique_ptr<IdentityProvider> identity_provider,
+      GURL assigner_url,
+      const AssignmentResultCallback& assignment_received_callback,
+      const AuthErrorCallback& error_callback);
+
+  ~AssignmentFetcher();
+
+  void Fetch();
+
+  IdentitySource* GetIdentitySource();
+
+ private:
+  // Called when an OAuth2 token is received.  Will then ask the
+  // AssignmentSource for an Assignment with this token.
+  void OnAuthTokenReceived(const std::string& client_auth_token);
+
+  // Provide OAuth2 token and propagate account sign in states change.
+  std::unique_ptr<IdentitySource> identity_source_;
+
+  AssignmentResultCallback assignment_received_callback_;
+
+  // Returns the URL to use for connections to the assigner. Used to construct
+  // the AssignmentSource.
+  GURL assigner_url_;
+
+  // The AssignmentSource is used when the user of AssignmentFetcher calls
+  // Fetch() to get a valid assignment and later connect to the engine.
+  std::unique_ptr<AssignmentSource> assignment_source_;
+
+  // The task runner to use for IO operations.
+  scoped_refptr<base::SingleThreadTaskRunner> io_thread_task_runner_;
+
+  // The task runner to use for file operations.
+  scoped_refptr<base::SingleThreadTaskRunner> file_thread_task_runner_;
+
+  DISALLOW_COPY_AND_ASSIGN(AssignmentFetcher);
+};
+
+}  // namespace client
+}  // namespace blimp
+
+#endif  // BLIMP_CLIENT_CORE_CONTEXT_ASSIGNMENT_FETCHER_H_