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

chrome/browser/interests/interests_fetcher.cc

+// 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.
+
+#include "chrome/browser/interests/interests_fetcher.h"
+
+#include "base/json/json_reader.h"
+#include "base/logging.h"
+#include "base/values.h"
+#include "net/base/load_flags.h"
+#include "net/http/http_status_code.h"
+#include "net/url_request/url_fetcher.h"
+#include "net/url_request/url_fetcher_factory.h"

[Marc Treib, 2015/09/22 12:02:59]

not needed

[tache, 2015/09/29 09:33:34]

Done.

+#include "net/url_request/url_request_context_getter.h"
+#include "net/url_request/url_request_status.h"
+
+using net::URLFetcher;
+using net::URLFetcherDelegate;
+using net::URLRequestContextGetter;
+using net::URLRequestStatus;
+using net::URLFetcherFactory;

[Marc Treib, 2015/09/22 12:02:59]

not needed

[tache, 2015/09/29 09:33:33]

Done.

+
+namespace {
+
+const int kNumRetries = 1;
+const char kIdInterests[] = "interest";
+const char kIdInterestName[] = "name";
+const char kIdInterestImageUrl[] = "imageUrl";
+const char kIdInterestRelevance[] = "relevance";
+
+const char kInterestsUrl[] = "https://www.googleapis.com/TBD/v1/interests";

[Marc Treib, 2015/09/22 12:02:59]

Do we know the correct URL? (Even if it doesn't actually work yet)

[tache, 2015/09/29 09:33:34]

This should be
https://www-googleapis-test.sandbox.google.com/chromenow/contextdemo

+
+std::vector<InterestsFetcher::Interest> EmptyResponse() {
+  return std::vector<InterestsFetcher::Interest>();
+}
+
+}  // namespace
+
+InterestsFetcher::InterestsFetcher(
+    net::URLRequestContextGetter* url_request_context,
+    const std::string& access_token)
+    : url_request_context_(url_request_context),
+      access_token_(access_token) {
+}
+
+void InterestsFetcher::Start(
+    const InterestsFetcher::InterestsCallback& callback) {
+  DCHECK(callback_.is_null());
+  callback_ = callback;
+
+  fetcher_ = CreateFetcher();
+
+  // Setup fetcher
+  fetcher_->SetRequestContext(url_request_context_);
+  fetcher_->SetLoadFlags(net::LOAD_DO_NOT_SEND_COOKIES |
+                         net::LOAD_DO_NOT_SAVE_COOKIES);
+  fetcher_->SetAutomaticallyRetryOnNetworkChanges(kNumRetries);
+
+  // Add oauth access token
+  fetcher_->AddExtraRequestHeader(std::string("Authorization: Bearer ") +
+                                  access_token_);
+
+  fetcher_->Start();
+}
+
+scoped_ptr<URLFetcher> InterestsFetcher::CreateFetcher() {
+  return URLFetcher::Create(GURL(kInterestsUrl), URLFetcher::GET, this);
+}
+
+void InterestsFetcher::OnURLFetchComplete(const net::URLFetcher* source) {
+  const URLRequestStatus& status = source->GetStatus();
+
+  if (!status.is_success()) {
+    DLOG(WARNING) << "URL request failed!";
+    callback_.Run(EmptyResponse());
+    return;
+  }
+
+  std::string response_body;
+  source->GetResponseAsString(&response_body);
+
+  callback_.Run(ExtractInterests(response_body));
+}
+
+std::vector<InterestsFetcher::Interest> InterestsFetcher::ExtractInterests(
+    const std::string& response) {
+  scoped_ptr<base::Value> value = base::JSONReader::Read(response);
+
+  const base::DictionaryValue* dict = nullptr;
+  if (!value || !value->GetAsDictionary(&dict)) {
+    DLOG(WARNING) << "ExtractInterests failed to parse global dictionary";
+    return EmptyResponse();
+  }
+
+  const base::ListValue* interests_list = nullptr;
+  std::vector<Interest> res;
+
+  if (!dict->GetList(kIdInterests, &interests_list)) {
+    DLOG(WARNING) << "ExtractInterests failed to parse interests list";
+    return EmptyResponse();
+  }
+
+  for (const base::Value* entry : *interests_list) {
+    const base::DictionaryValue* interest_dict = nullptr;
+    if (!entry->GetAsDictionary(&interest_dict)) {
+      DLOG(WARNING) << "ExtractInterests failed to parse interest dictionary";
+      return EmptyResponse();
+    }
+
+    std::string name;
+    if (!interest_dict->GetString(kIdInterestName, &name)) {
+      DLOG(WARNING) << "ExtractInterests failed to parse interest name";
+      return EmptyResponse();
+    }
+
+    std::string image_url;
+    if (!interest_dict->GetString(kIdInterestImageUrl, &image_url)) {
+      // image_url is allowed to be missing.
+      //
+      // However this is still logged as a warning, since, currently, the server
+      // should always provide an image_url.
+      //

[Marc Treib, 2015/09/22 12:02:59]

nit: remove empty comment line

[tache, 2015/09/29 09:33:33]

Done.

+      DLOG(WARNING) << "ExtractInterests failed to parse interest image URL";
+    }
+
+    double relevance;
+    if (!interest_dict->GetDouble(kIdInterestRelevance, &relevance)) {
+      DLOG(WARNING) << "ExtractInterests failed to parse interest relevance";
+      return EmptyResponse();
+    }
+
+    res.push_back(Interest{name, image_url, relevance});
+  }
+
+  return res;
+}
+
+InterestsFetcher::~InterestsFetcher() {}
+
+bool InterestsFetcher::Interest::operator==(const Interest& interest) const {
+  return name == interest.name &&
+      image_url == interest.image_url &&
+      relevance == interest.relevance;
+}