Add InterestsFetcher which retrieves a user's interests from the server.

chrome/browser/interests/interests_fetcher.h

+// Copyright 2015 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_INTERESTS_INTERESTS_FETCHER_H_
+#define CHROME_BROWSER_INTERESTS_INTERESTS_FETCHER_H_
+
+#include <string>
+#include <vector>
+
+#include "base/callback.h"
+#include "base/gtest_prod_util.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "chrome/browser/profiles/profile.h"
+#include "components/signin/core/browser/signin_manager.h"
+#include "google_apis/gaia/oauth2_token_service.h"
+#include "net/url_request/url_fetcher.h"
+#include "net/url_request/url_fetcher_delegate.h"
+
+
+// Class to asynchronously retrieve the topics of interests for a user.
+// Authentication is done using the user's OAuth access_token.
+//
+// The instance of this class should be deleted after the callback has been
+// called else the request will be aborted.

[Bernhard Bauer, 2015/09/29 14:01:12]

What does this comment mean? How can the request be aborted after the callback
has already been run?

[tache, 2015/09/29 19:58:24]

Sorry about that. Hope now it's clear.

+//
+// Example Usage:
+//
+// auto request = make_scoped_ptr(new InterestsFetcher(callback));
+//
+class InterestsFetcher : public net::URLFetcherDelegate,
+                         public OAuth2TokenService::Consumer {
+ public:
+  struct Interest {
+    std::string name;
+    std::string image_url;

[Bernhard Bauer, 2015/09/29 14:01:12]

Could this be a GURL?

[tache, 2015/09/29 19:58:24]

Done.

+    double relevance;
+
+    bool operator==(const Interest& interest) const;
+  };
+
+  typedef base::Callback<void(const std::vector<Interest>&)>
+      InterestsCallback;
+
+  InterestsFetcher(
+      OAuth2TokenService* oauth2_token_service,
+      const std::string& account_id,
+      net::URLRequestContextGetter* context);
+
+  ~InterestsFetcher() override;
+
+  static scoped_ptr<InterestsFetcher> CreateFromProfile(Profile* profile);
+
+  void Start(const InterestsCallback& callback);
+
+
+ private:
+  // net::URLFetcherDelegate implementation.
+  void OnURLFetchComplete(const net::URLFetcher* source) override;
+
+
+  void OnGetTokenSuccess(const OAuth2TokenService::Request* request,

[Bernhard Bauer, 2015/09/29 14:01:12]

Also document which interface these methods implement.

[tache, 2015/09/29 19:58:24]

Done.

+                         const std::string& access_token,
+                         const base::Time& experiation_time) override;
+
+  void OnGetTokenFailure(const OAuth2TokenService::Request* request,
+                         const GoogleServiceAuthError& error) override;
+
+  scoped_ptr<net::URLFetcher> CreateFetcher();
+
+  // parse the json response

[Bernhard Bauer, 2015/09/29 14:01:12]

Capitalize the beginning of the sentence, and end it with a period.

[tache, 2015/09/29 19:58:24]

Done.

+  std::vector<Interest> ExtractInterests(const std::string& response);
+
+
+  InterestsCallback callback_;
+
+  scoped_ptr<net::URLFetcher> fetcher_;
+
+  scoped_ptr<OAuth2TokenService::Request> oauth_request_;
+
+  OAuth2TokenService* token_service_;
+
+  std::string account_id_;
+
+  net::URLRequestContextGetter* url_request_context_;
+
+
+  DISALLOW_COPY_AND_ASSIGN(InterestsFetcher);
+};
+
+#endif  // CHROME_BROWSER_INTERESTS_INTERESTS_FETCHER_H_