Fetch snippets from ChromeReader and show them on the NTP

components/ntp_snippets/ntp_snippets_fetcher.h

Index: components/ntp_snippets/ntp_snippets_fetcher.h
diff --git a/components/ntp_snippets/ntp_snippets_fetcher.h b/components/ntp_snippets/ntp_snippets_fetcher.h
new file mode 100644
index 0000000000000000000000000000000000000000..6ce9af3ca49042504f108724131faffb3ba05c13
--- /dev/null
+++ b/components/ntp_snippets/ntp_snippets_fetcher.h
@@ -0,0 +1,90 @@
+// 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/memory/weak_ptr.h"
+#include "base/observer_list.h"
+#include "base/sequenced_task_runner.h"
+#include "components/signin/core/browser/signin_tracker.h"

[Bernhard Bauer, 2016/02/08 18:19:26]

Do you need this, or SigninManager (which you could forward-declare)?

[May, 2016/02/09 17:38:53]

Done.

+#include "google_apis/gaia/oauth2_token_service.h"
+
+namespace net {
+class URLRequestContextGetter;
+class URLFetcher;
+class URLFetcherDelegate;
+}  // namespace net
+
+namespace ntp_snippets {
+
+// Fetches snippet data for the NTP from the server
+class NTPSnippetsFetcher : public KeyedService,

[Bernhard Bauer, 2016/02/08 18:19:26]

I don't think this should be a KeyedService if it's owned by the
NTPSnippetsService.

[May, 2016/02/09 17:38:53]

You're right, leftover crud from original way I wrote it.

+                           public OAuth2TokenService::Consumer,
+                           public OAuth2TokenService::Observer,
+                           public net::URLFetcherDelegate {
+ public:
+  class Observer {
+   public:
+    // Send everytime the a new set of snippets is downloaded
+    virtual void OnNTPSnippetsDownloaded() = 0;

[Bernhard Bauer, 2016/02/08 18:19:26]

Instead of a single-method interface, consider using a base::Callback and
base::CallbackList instead of an ObserverList.

[May, 2016/02/09 17:38:53]

Done.

+
+   protected:
+    virtual ~Observer() {}
+  };
+
+  explicit NTPSnippetsFetcher(

[Marc Treib, 2016/02/09 09:17:54]

explicit is only useful for single-argument constructors

[May, 2016/02/09 17:38:53]

Done.

+      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);
+
+  // Observer accessors.
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
+ 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_;
+
+  base::ObserverList<Observer> observers_;
+
+  base::WeakPtrFactory<NTPSnippetsFetcher> weak_ptr_factory_;

[Bernhard Bauer, 2016/02/08 18:19:26]

Add DISALLOW_COPY_AND_ASSIGN.

[May, 2016/02/09 17:38:53]

Done.

+};
+}  // namespace ntp_snippets
+
+#endif  // COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_FETCHER_H_