Fetch snippets from ChromeReader and show them on the NTP

components/ntp_snippets/ntp_snippets_fetcher.h

+// 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 COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_FETCHER_H_
+#define COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_FETCHER_H_
+
+#include "base/callback.h"
+#include "base/callback_list.h"
+#include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
+#include "base/sequenced_task_runner.h"
+#include "google_apis/gaia/oauth2_token_service.h"
+
+namespace base {
+class FilePath;
+}  // namespace base
+
+namespace net {
+class URLRequestContextGetter;
+class URLFetcher;
+class URLFetcherDelegate;
+}  // namespace net
+
+class SigninManager;
+
+namespace ntp_snippets {
+
+// Fetches snippet data for the NTP from the server
+class NTPSnippetsFetcher : public OAuth2TokenService::Consumer,
+                           public OAuth2TokenService::Observer,
+                           public net::URLFetcherDelegate {
+ public:
+  using SnippetsAvailableCallback = base::Callback<void(const base::FilePath&)>;
+  using SnippetsAvailableCallbackList =
+      base::CallbackList<void(const base::FilePath&)>;
+
+  NTPSnippetsFetcher(scoped_refptr<base::SequencedTaskRunner> file_task_runner,
+                     SigninManager* signin_manager,
+                     OAuth2TokenService* oauth2_token_service,
+                     net::URLRequestContextGetter* url_request_context_getter);
+  virtual ~NTPSnippetsFetcher();
+
+  // Fetches snippets from the server. |overwrite| is true if existing snippets
+  // should be overwritten.
+  void FetchSnippets(bool overwrite);
+
+  // Adds a callback that is called when a new set of snippets are downloaded
+  scoped_ptr<SnippetsAvailableCallbackList::Subscription> AddCallback(
+      const SnippetsAvailableCallback& callback) WARN_UNUSED_RESULT;
+
+ private:
+  void StartTokenRequest();
+  void NotifyObservers();
+  void OnDownloadSnippetsDone(bool success);
+  void OnFileExistsCheckDone(bool exists);
+  void OnFileMoveDone(bool success);
+  void StartFetch();
+
+  // OAuth2TokenService::Consumer overrides:
+  void OnGetTokenSuccess(const OAuth2TokenService::Request* request,
+                         const std::string& access_token,
+                         const base::Time& expiration_time) override;
+  void OnGetTokenFailure(const OAuth2TokenService::Request* request,
+                         const GoogleServiceAuthError& error) override;
+
+  // OAuth2TokenService::Observer overrides:
+  void OnRefreshTokenAvailable(const std::string& account_id) override;
+
+  // URLFetcherDelegate implementation.
+  void OnURLFetchComplete(const net::URLFetcher* source) override;
+
+  // The SequencedTaskRunner on which file system operations will be run.
+  scoped_refptr<base::SequencedTaskRunner> file_task_runner_;
+
+  // Holds the URL request context. Not owned.
+  net::URLRequestContextGetter* url_request_context_getter_;
+
+  scoped_ptr<net::URLFetcher> url_fetcher_;
+  scoped_ptr<SigninManager> signin_manager_;
+  scoped_ptr<OAuth2TokenService> token_service_;
+  scoped_ptr<OAuth2TokenService::Request> oauth_request_;
+
+  SnippetsAvailableCallbackList callback_list_;
+
+  base::WeakPtrFactory<NTPSnippetsFetcher> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(NTPSnippetsFetcher);
+};
+}  // namespace ntp_snippets
+
+#endif  // COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_FETCHER_H_