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/command_line.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 "chrome/common/chrome_switches.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"
+
+namespace {
+
+const int kNumRetries = 1;
+const char kIdInterests[] = "interests";
+const char kIdInterestName[] = "name";
+const char kIdInterestImageUrl[] = "imageUrl";
+const char kIdInterestRelevance[] = "relevance";
+
+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>();
+}
+
+GURL GetInterestsURL() {
+  const base::CommandLine* command_line =
+      base::CommandLine::ForCurrentProcess();
+  GURL interests_url(
+      command_line->GetSwitchValueASCII(switches::kInterestsURL));

[Bernhard Bauer, 2015/10/06 08:56:10]

You can inline the constructor (`return GURL(...);`)

[PEConn, 2015/10/06 10:11:44]

Done.

+  return interests_url;
+}
+
+}  // namespace
+
+InterestsFetcher::Interest::Interest(const std::string& name,
+                                     const GURL& image_url, float relevance)

[Bernhard Bauer, 2015/10/06 08:56:10]

The items in argument lists go either all on the same line, or each on a
separate line.

(Tip: run `git cl format`, which should fix things like that.)

[PEConn, 2015/10/06 10:11:44]

Done.

+    : name(name), image_url(image_url), relevance(relevance) {}
+
+InterestsFetcher::Interest::~Interest() {}
+
+bool InterestsFetcher::Interest::operator==(const Interest& interest) const {
+  return name == interest.name &&
+      image_url == interest.image_url &&
+      relevance == interest.relevance;
+}
+
+InterestsFetcher::InterestsFetcher(
+    OAuth2TokenService* oauth2_token_service,
+    const std::string& account_id,
+    net::URLRequestContextGetter* url_request_context)
+    : OAuth2TokenService::Consumer("interests_fetcher"),
+      account_id_(account_id),
+      url_request_context_(url_request_context),
+      access_token_expired_(false),
+      token_service_(oauth2_token_service) {
+}
+
+InterestsFetcher::~InterestsFetcher() {}
+
+// 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::FetchInterests(
+    const InterestsFetcher::InterestsCallback& callback) {
+  DCHECK(callback_.is_null());
+  callback_ = callback;
+  StartOAuth2Request();
+}
+
+void InterestsFetcher::OnURLFetchComplete(const net::URLFetcher* source) {
+  const net::URLRequestStatus& status = source->GetStatus();
+  if (!status.is_success()) {
+    VLOG(2) << "Network error " << status.error();
+    callback_.Run(EmptyResponse());
+    return;
+  }
+
+  int response_code = source->GetResponseCode();
+  // If we get an authorization error, refresh token and retry once.
+  if (response_code == net::HTTP_UNAUTHORIZED && !access_token_expired_) {
+    access_token_expired_ = true;
+    token_service_->InvalidateAccessToken(account_id_, GetApiScopes(),
+                                          access_token_);
+    StartOAuth2Request();
+    return;
+  }
+
+  if (response_code != net::HTTP_OK) {
+    VLOG(2) << "HTTP error " << response_code;
+    callback_.Run(EmptyResponse());
+    return;
+  }
+
+  std::string response_body;
+  source->GetResponseAsString(&response_body);
+
+  callback_.Run(ExtractInterests(response_body));
+}
+
+void InterestsFetcher::OnGetTokenSuccess(
+    const OAuth2TokenService::Request* request,
+    const std::string& access_token,
+    const base::Time& expiration_time) {
+  access_token_ = access_token;
+
+  fetcher_ = CreateFetcher();
+  fetcher_->SetRequestContext(url_request_context_);
+  fetcher_->SetLoadFlags(net::LOAD_DO_NOT_SEND_COOKIES |
+                         net::LOAD_DO_NOT_SAVE_COOKIES);
+  fetcher_->SetAutomaticallyRetryOnNetworkChanges(kNumRetries);
+
+  fetcher_->AddExtraRequestHeader(
+      base::StringPrintf(kAuthorizationHeaderFormat, access_token_.c_str()));
+
+  fetcher_->Start();
+}
+
+void InterestsFetcher::OnGetTokenFailure(
+    const OAuth2TokenService::Request* request,
+    const GoogleServiceAuthError& error) {
+  DLOG(WARNING) << error.ToString();
+
+  callback_.Run(EmptyResponse());
+}
+
+void InterestsFetcher::StartOAuth2Request(){
+  oauth_request_ =
+      token_service_->StartRequest(account_id_, GetApiScopes(), this);
+}
+
+OAuth2TokenService::ScopeSet InterestsFetcher::GetApiScopes() {
+  OAuth2TokenService::ScopeSet scopes;
+  scopes.insert(kApiScope);
+  return scopes;
+}
+
+scoped_ptr<net::URLFetcher> InterestsFetcher::CreateFetcher() {
+  return net::URLFetcher::Create(0, GetInterestsURL(), net::URLFetcher::GET,
+                                 this);
+}
+
+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, 2015/10/06 08:56:10]

If you move this to the beginning, you can just return res below instead of
EmptyResponse() (which you could then remove).

[PEConn, 2015/10/06 10:11:44]

I think EmptyResponse makes things a bit more readable, however I've moved parts
around to make things a bit more logically grouped.

+
+  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, GURL(image_url), relevance});
+  }
+
+  return res;
+}