Local NTP: Introduce OneGoogleBarFetcher

chrome/browser/search/one_google_bar/one_google_bar_fetcher.h

Index: chrome/browser/search/one_google_bar/one_google_bar_fetcher.h
diff --git a/chrome/browser/search/one_google_bar/one_google_bar_fetcher.h b/chrome/browser/search/one_google_bar/one_google_bar_fetcher.h
new file mode 100644
index 0000000000000000000000000000000000000000..4b42d42114bd4c174154f0ae19967ecd6c443ce8
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+++ b/chrome/browser/search/one_google_bar/one_google_bar_fetcher.h
@@ -0,0 +1,24 @@
+// 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.
+
+#ifndef CHROME_BROWSER_SEARCH_ONE_GOOGLE_BAR_ONE_GOOGLE_BAR_FETCHER_H_
+#define CHROME_BROWSER_SEARCH_ONE_GOOGLE_BAR_ONE_GOOGLE_BAR_FETCHER_H_
+
+#include "base/callback_forward.h"
+#include "base/optional.h"
+
+struct OneGoogleBarData;
+
+// Interface for fetching OneGoogleBarData over the network.
+class OneGoogleBarFetcher {
+ public:
+  using OneGoogleCallback =
+      base::OnceCallback<void(const base::Optional<OneGoogleBarData>&)>;
+
+  // Initiates a fetch from the network. On completion (successful or not), the
+  // callback will be called with the result, which will be nullopt on failure.
+  virtual void Fetch(OneGoogleCallback callback) = 0;
+};
+
+#endif  // CHROME_BROWSER_SEARCH_ONE_GOOGLE_BAR_ONE_GOOGLE_BAR_FETCHER_H_