Introduce a Doodle Fetcher for NTP

components/doodle/doodle_fetcher.h

Index: components/doodle/doodle_fetcher.h
diff --git a/components/doodle/doodle_fetcher.h b/components/doodle/doodle_fetcher.h
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+++ b/components/doodle/doodle_fetcher.h
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+// 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 COMPONENTS_DOODLE_DOODLE_FETCHER_H_
+#define COMPONENTS_DOODLE_DOODLE_FETCHER_H_
+
+#include <memory>
+#include <string>
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "net/url_request/url_fetcher_delegate.h"
+
+namespace base {
+class DictionaryValue;
+class Value;
+}
+
+namespace net {
+class URLRequestContextGetter;
+}
+
+using ParseJSONCallback = base::Callback<void(
+    const std::string& unsafe_json,
+    const base::Callback<void(std::unique_ptr<base::Value>)>& success_callback,
+    const base::Callback<void(const std::string&)>& error_callback)>;
+
+struct DoodleImage {
+  std::string url;
+  int height;
+  int width;
+  std::string background_color;
+};
+
+struct DoodleConfig {
+  DoodleConfig();
+  DoodleConfig(DoodleImage large_image);
+  DoodleConfig(const DoodleConfig& config);
+  bool error_during_fetch;
+  std::string search_url;
+  std::string fullpage_interactive_url;
+  DoodleImage large_image;
+};
+
+class DoodleFetcher : public net::URLFetcherDelegate {
+ public:
+  using FinishedCallback = base::Callback<void(DoodleConfig doodle_config)>;
+
+  DoodleFetcher(net::URLRequestContextGetter* download_context,
+                ParseJSONCallback parse_json);
+
+  ~DoodleFetcher() override;
+
+  void FetchDoodle(const FinishedCallback& callback);
+
+ private:
+  // net::URLFetcherDelegate implementation.
+  void OnURLFetchComplete(const net::URLFetcher* source) override;
+
+  void OnJsonParsed(std::unique_ptr<base::Value> json);
+  void OnJsonParseFailed(const std::string& error_message);
+  void ParseDoodle(std::unique_ptr<base::DictionaryValue> config);
+  void OnDownloadFailed();
+
+  // Parameters set from constructor.
+  net::URLRequestContextGetter* const download_context_;
+  ParseJSONCallback parse_json_;
+
+  FinishedCallback callback_;
+
+  std::unique_ptr<net::URLFetcher> fetcher_;
+
+  base::WeakPtrFactory<DoodleFetcher> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(DoodleFetcher);
+};
+
+#endif  // COMPONENTS_DOODLE_DOODLE_FETCHER_H_