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

chrome/browser/interests/interests_fetcher.cc

Index: chrome/browser/interests/interests_fetcher.cc
diff --git a/chrome/browser/interests/interests_fetcher.cc b/chrome/browser/interests/interests_fetcher.cc
new file mode 100644
index 0000000000000000000000000000000000000000..1c355525e565e2724a3a4c5a53bb2bc75e108dc4
--- /dev/null
+++ b/chrome/browser/interests/interests_fetcher.cc
@@ -0,0 +1,188 @@
+// 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/strings/stringprintf.h"
+#include "base/values.h"
+#include "chrome/browser/signin/profile_oauth2_token_service_factory.h"
+#include "chrome/browser/signin/signin_manager_factory.h"
+#include "components/signin/core/browser/profile_oauth2_token_service.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_request_context_getter.h"
+#include "net/url_request/url_request_status.h"
+
+using net::URLFetcher;
+using net::URLFetcherDelegate;
+using net::URLRequestContextGetter;
+using net::URLRequestStatus;
+
+namespace {
+
+const int kNumRetries = 1;
+const char kIdInterests[] = "interests";
+const char kIdInterestName[] = "name";
+const char kIdInterestImageUrl[] = "imageUrl";
+const char kIdInterestRelevance[] = "relevance";
+
+const char kInterestsUrl[] =
+    "https://www-googleapis-stagin.sandbox.google.com/chromenow/contextdemo/"

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

stagin? Also, instead of referencing internal URLs in Chromium code, prefer
passing the URL in via a command line flag.

[tache, 2015/09/29 19:58:23]

Done.

+    "interests/";
+const char kApiScope[] = "https://www.googleapis.com/auth/googlenow";
+
+const char kAuthorizationHeaderFormat[] = "Authorization: Bearer %s";
+
+std::vector<InterestsFetcher::Interest> EmptyResponse() {
+  return std::vector<InterestsFetcher::Interest>();
+}
+
+}  // namespace
+
+InterestsFetcher::InterestsFetcher(
+    OAuth2TokenService* oauth2_token_service,
+    const std::string& account_id,
+    net::URLRequestContextGetter* url_request_context)
+    : OAuth2TokenService::Consumer("interests_fetcher"),
+      token_service_(oauth2_token_service),
+      account_id_(account_id),
+      url_request_context_(url_request_context) {
+}
+
+// static
+scoped_ptr<InterestsFetcher>
+InterestsFetcher::CreateFromProfile(Profile* profile) {
+  ProfileOAuth2TokenService* token_service =
+       ProfileOAuth2TokenServiceFactory::GetForProfile(profile);
+
+   SigninManagerBase* signin = SigninManagerFactory::GetForProfile(profile);
+
+   return make_scoped_ptr(new InterestsFetcher(
+       token_service,
+       signin->GetAuthenticatedAccountId(),
+       profile->GetRequestContext()));
+}
+
+void InterestsFetcher::Start(
+    const InterestsFetcher::InterestsCallback& callback) {
+  DCHECK(callback_.is_null());
+  callback_ = callback;
+
+  OAuth2TokenService::ScopeSet scopes;
+  scopes.insert(kApiScope);
+
+  oauth_request_ = token_service_->StartRequest(account_id_, scopes, this);
+}
+
+void InterestsFetcher::OnGetTokenFailure(
+    const OAuth2TokenService::Request* request,
+    const GoogleServiceAuthError& error) {
+  DLOG(WARNING) << error.ToString();
+
+  callback_.Run(EmptyResponse());
+}
+
+void InterestsFetcher::OnGetTokenSuccess(
+    const OAuth2TokenService::Request* request,
+    const std::string& access_token,
+    const base::Time& expiration_time) {
+
+  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(
+      base::StringPrintf(kAuthorizationHeaderFormat, access_token.c_str()));
+
+  fetcher_->Start();
+
+}
+
+
+scoped_ptr<URLFetcher> InterestsFetcher::CreateFetcher() {
+  return URLFetcher::Create(0, 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!";

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

At least include the status in the log message.

[tache, 2015/09/29 19:58:23]

Done.

+    callback_.Run(EmptyResponse());
+    return;
+  }
+
+  std::string response_body;
+  source->GetResponseAsString(&response_body);

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

This doesn't seem to deal with HTTP errors, including ones thrown by an expired
access token.

[tache, 2015/09/29 19:58:23]

Improved logging in case of HTTP errors.

Also in the case of an authorization error, the access token is invalidated and
the request is retried.

+
+  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;

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

If you declare this further up, you could just always return this instead of
calling EmptyResponse().

[tache, 2015/09/29 19:58:23]

I also use EmptyResponse() in other methods for the return value in case of an
error. I think it is better, for consistency, to explicitly call it.

+
+  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.
+      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;
+}