components/feed/core/feed_networking_host.cc - chromium/src.git - Git at Google

 // Copyright 2018 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 "components/feed/core/feed_networking_host.h"

 #include <utility>

 #include "base/bind.h"
 #include "base/metrics/field_trial_params.h"
 #include "base/metrics/histogram_functions.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/stringprintf.h"
 #include "base/time/tick_clock.h"
 #include "base/time/time.h"
 #include "base/values.h"
 #include "components/feed/core/common/pref_names.h"
 #include "components/feed/feed_feature_list.h"
 #include "components/prefs/pref_service.h"
 #include "components/signin/public/identity_manager/access_token_info.h"
 #include "components/signin/public/identity_manager/identity_manager.h"
 #include "components/signin/public/identity_manager/primary_account_access_token_fetcher.h"
 #include "components/signin/public/identity_manager/scope_set.h"
 #include "components/variations/net/variations_http_headers.h"
 #include "google_apis/gaia/google_service_auth_error.h"
 #include "net/base/load_flags.h"
 #include "net/base/url_util.h"
 #include "net/http/http_response_headers.h"
 #include "net/http/http_status_code.h"
 #include "net/traffic_annotation/network_traffic_annotation.h"
 #include "services/network/public/cpp/resource_request.h"
 #include "services/network/public/cpp/resource_request_body.h"
 #include "services/network/public/cpp/shared_url_loader_factory.h"
 #include "services/network/public/cpp/simple_url_loader.h"
 #include "services/network/public/mojom/url_response_head.mojom.h"

 #include "third_party/zlib/google/compression_utils.h"

 using IdentityManager = signin::IdentityManager;

 namespace {

 constexpr char kApiKeyQueryParam[] = "key";
 constexpr char kAuthenticationScope[] =
     "https://www.googleapis.com/auth/googlenow";
 constexpr char kAuthorizationRequestHeaderFormat[] = "Bearer %s";

 constexpr char kContentEncoding[] = "Content-Encoding";
 constexpr char kContentType[] = "application/octet-stream";
 constexpr char kGzip[] = "gzip";

 }  // namespace

 namespace feed {

 // NetworkFetch is a helper class internal to the networking host. Each
 // instance represents a single "logical" fetch that ends by calling the
 // associated callback. Network fetches will actually attempt two fetches if
 // there is a signed in user; the first to retrieve an access token, and the
 // second to the specified url.
 class NetworkFetch {
  public:
   NetworkFetch(const GURL& url,
                const std::string& request_type,
                std::vector<uint8_t> request_body,
                IdentityManager* identity_manager,
                network::SharedURLLoaderFactory* loader_factory,
                const std::string& api_key,
                const base::TickClock* tick_clock,
                PrefService* pref_service);

   void Start(FeedNetworkingHost::ResponseCallback done_callback);

  private:
   void StartAccessTokenFetch();
   void AccessTokenFetchFinished(base::TimeTicks token_start_ticks,
                                 GoogleServiceAuthError error,
                                 signin::AccessTokenInfo access_token_info);
   void StartLoader();
   std::unique_ptr<network::SimpleURLLoader> MakeLoader();
   void SetRequestHeaders(bool has_request_body,
                          network::ResourceRequest* request) const;
   void PopulateRequestBody(network::SimpleURLLoader* loader);
   void OnSimpleLoaderComplete(std::unique_ptr<std::string> response);

   GURL url_;
   const std::string request_type_;
   std::string access_token_;
   const std::vector<uint8_t> request_body_;
   IdentityManager* const identity_manager_;
   std::unique_ptr<signin::PrimaryAccountAccessTokenFetcher> token_fetcher_;
   std::unique_ptr<network::SimpleURLLoader> simple_loader_;
   FeedNetworkingHost::ResponseCallback done_callback_;
   network::SharedURLLoaderFactory* loader_factory_;
   const std::string api_key_;
   const base::TickClock* tick_clock_;

   // Set when the NetworkFetch is constructed, before token and article fetch.
   const base::TimeTicks entire_send_start_ticks_;

   // Should be set right before the article fetch, and after the token fetch if
   // there is one.
   base::TimeTicks loader_only_start_ticks_;
   PrefService* pref_service_;
   bool host_overridden_ = false;

   DISALLOW_COPY_AND_ASSIGN(NetworkFetch);
 };

 NetworkFetch::NetworkFetch(const GURL& url,
                            const std::string& request_type,
                            std::vector<uint8_t> request_body,
                            IdentityManager* identity_manager,
                            network::SharedURLLoaderFactory* loader_factory,
                            const std::string& api_key,
                            const base::TickClock* tick_clock,
                            PrefService* pref_service)
     : url_(url),
       request_type_(request_type),
       request_body_(std::move(request_body)),
       identity_manager_(identity_manager),
       loader_factory_(loader_factory),
       api_key_(api_key),
       tick_clock_(tick_clock),
       entire_send_start_ticks_(tick_clock_->NowTicks()),
       pref_service_(pref_service) {
   // Apply the host override (from snippets-internals).
   std::string host_override =
       pref_service_->GetString(feed::prefs::kHostOverrideHost);
   if (!host_override.empty()) {
     GURL override_host_url(host_override);
     if (override_host_url.is_valid()) {
       GURL::Replacements replacements;
       replacements.SetSchemeStr(override_host_url.scheme_piece());
       replacements.SetHostStr(override_host_url.host_piece());
       replacements.SetPortStr(override_host_url.port_piece());
       url_ = url_.ReplaceComponents(replacements);
       host_overridden_ = true;
     }
   }
 }

 void NetworkFetch::Start(FeedNetworkingHost::ResponseCallback done_callback) {
   done_callback_ = std::move(done_callback);

   if (!identity_manager_->HasPrimaryAccount()) {
     StartLoader();
     return;
   }

   StartAccessTokenFetch();
 }

 void NetworkFetch::StartAccessTokenFetch() {
   signin::ScopeSet scopes{kAuthenticationScope};
   // It's safe to pass base::Unretained(this) since deleting the token fetcher
   // will prevent the callback from being completed.
   token_fetcher_ = std::make_unique<signin::PrimaryAccountAccessTokenFetcher>(
       "feed", identity_manager_, scopes,
       base::BindOnce(&NetworkFetch::AccessTokenFetchFinished,
                      base::Unretained(this), tick_clock_->NowTicks()),
       signin::PrimaryAccountAccessTokenFetcher::Mode::kWaitUntilAvailable);
 }

 void NetworkFetch::AccessTokenFetchFinished(
     base::TimeTicks token_start_ticks,
     GoogleServiceAuthError error,
     signin::AccessTokenInfo access_token_info) {
   UMA_HISTOGRAM_ENUMERATION("ContentSuggestions.Feed.Network.TokenFetchStatus",
                             error.state(), GoogleServiceAuthError::NUM_STATES);

   base::TimeDelta token_duration = tick_clock_->NowTicks() - token_start_ticks;
   UMA_HISTOGRAM_MEDIUM_TIMES("ContentSuggestions.Feed.Network.TokenDuration",
                              token_duration);

   access_token_ = access_token_info.token;
   StartLoader();
 }

 void NetworkFetch::StartLoader() {
   loader_only_start_ticks_ = tick_clock_->NowTicks();
   simple_loader_ = MakeLoader();
   simple_loader_->DownloadToStringOfUnboundedSizeUntilCrashAndDie(
       loader_factory_, base::BindOnce(&NetworkFetch::OnSimpleLoaderComplete,
                                       base::Unretained(this)));
 }

 std::unique_ptr<network::SimpleURLLoader> NetworkFetch::MakeLoader() {
   // TODO(pnoland): Add data use measurement once it's supported for simple
   // url loader.
   net::NetworkTrafficAnnotationTag traffic_annotation =
       net::DefineNetworkTrafficAnnotation("interest_feed_send", R"(
         semantics {
           sender: "Feed Library"
           description: "Chrome can show content suggestions (e.g. articles) "
           "in the form of a feed. For signed-in users, these may be "
           "personalized based on the user's synced browsing history."
           trigger: "Triggered periodically in the background, or upon "
           "explicit user request."
           data: "The locale of the device and data describing the suggested "
             "content that the user interacted with. For signed in users "
             "the request is authenticated. "
           destination: GOOGLE_OWNED_SERVICE
         }
         policy {
           cookies_allowed: YES
           cookies_store: "user"
           setting: "This can be disabled from the New Tab Page by collapsing "
           "the articles section."
           chrome_policy {
             NTPContentSuggestionsEnabled {
               policy_options {mode: MANDATORY}
               NTPContentSuggestionsEnabled: false
             }
           }
         })");
   GURL url(url_);
   if (access_token_.empty() && !api_key_.empty())
     url = net::AppendQueryParameter(url_, kApiKeyQueryParam, api_key_);

   auto resource_request = std::make_unique<network::ResourceRequest>();
   resource_request->url = url;

   resource_request->load_flags = net::LOAD_BYPASS_CACHE;
   resource_request->credentials_mode = network::mojom::CredentialsMode::kOmit;
   resource_request->method = request_type_;

   // Include credentials ONLY if the user has overridden the feed host through
   // the internals page. This allows for some authentication workflows we need
   // for testing.
   if (host_overridden_) {
     resource_request->credentials_mode =
         network::mojom::CredentialsMode::kInclude;
     resource_request->site_for_cookies = net::SiteForCookies::FromUrl(url);
   }

   SetRequestHeaders(!request_body_.empty(), resource_request.get());

   auto simple_loader = network::SimpleURLLoader::Create(
       std::move(resource_request), traffic_annotation);
   simple_loader->SetAllowHttpErrorResults(true);
   simple_loader->SetTimeoutDuration(
       base::TimeDelta::FromSeconds(kTimeoutDurationSeconds.Get()));
   PopulateRequestBody(simple_loader.get());
   return simple_loader;
 }

 void NetworkFetch::SetRequestHeaders(bool has_request_body,
                                      network::ResourceRequest* request) const {
   if (has_request_body) {
     request->headers.SetHeader(net::HttpRequestHeaders::kContentType,
                                kContentType);
     request->headers.SetHeader(kContentEncoding, kGzip);
   }

   variations::SignedIn signed_in_status = variations::SignedIn::kNo;
   if (!access_token_.empty()) {
     std::string auth_header = base::StringPrintf(
         kAuthorizationRequestHeaderFormat, access_token_.c_str());
     request->headers.SetHeader(net::HttpRequestHeaders::kAuthorization,
                                auth_header);
     signed_in_status = variations::SignedIn::kYes;
   }

   // Add X-Client-Data header with experiment IDs from field trials.
   variations::AppendVariationsHeader(url_, variations::InIncognito::kNo,
                                      signed_in_status, request);
 }

 void NetworkFetch::PopulateRequestBody(network::SimpleURLLoader* loader) {
   std::string compressed_request_body;
   if (!request_body_.empty()) {
     std::string uncompressed_request_body(
         reinterpret_cast<const char*>(request_body_.data()),
         request_body_.size());

     compression::GzipCompress(uncompressed_request_body,
                               &compressed_request_body);

     loader->AttachStringForUpload(compressed_request_body, kContentType);
   }

   UMA_HISTOGRAM_COUNTS_1M(
       "ContentSuggestions.Feed.Network.RequestSizeKB.Compressed",
       static_cast<int>(compressed_request_body.size() / 1024));
 }

 void NetworkFetch::OnSimpleLoaderComplete(
     std::unique_ptr<std::string> response) {
   int32_t status_code = simple_loader_->NetError();
   // If overriding the feed host, try to grab the Bless nonce. This is
   // strictly informational, and only displayed in snippets-internals.
   if (host_overridden_ && simple_loader_->ResponseInfo()) {
     size_t iter = 0;
     std::string value;
     while (simple_loader_->ResponseInfo()->headers->EnumerateHeader(
         &iter, "www-authenticate", &value)) {
       size_t pos = value.find("nonce=\"");
       if (pos != std::string::npos) {
         std::string nonce = value.substr(pos + 7, 16);
         if (nonce.size() == 16) {
           pref_service_->SetString(feed::prefs::kHostOverrideBlessNonce, nonce);
           break;
         }
       }
     }
   }
   std::vector<uint8_t> response_body;

   if (response) {
     status_code = simple_loader_->ResponseInfo()->headers->response_code();

     if (status_code == net::HTTP_UNAUTHORIZED) {
       signin::ScopeSet scopes{kAuthenticationScope};
       CoreAccountId account_id = identity_manager_->GetPrimaryAccountId();
       if (!account_id.empty()) {
         identity_manager_->RemoveAccessTokenFromCache(account_id, scopes,
                                                       access_token_);
       }
     }

     const uint8_t* begin = reinterpret_cast<const uint8_t*>(response->data());
     const uint8_t* end = begin + response->size();
     response_body.assign(begin, end);
   }

   base::TimeDelta entire_send_duration =
       tick_clock_->NowTicks() - entire_send_start_ticks_;
   UMA_HISTOGRAM_MEDIUM_TIMES("ContentSuggestions.Feed.Network.Duration",
                              entire_send_duration);

   base::TimeDelta loader_only_duration =
       tick_clock_->NowTicks() - loader_only_start_ticks_;
   // This histogram purposefully matches name and bucket size used in
   // RemoteSuggestionsFetcherImpl.
   UMA_HISTOGRAM_TIMES("NewTabPage.Snippets.FetchTime", loader_only_duration);

   base::UmaHistogramSparse("ContentSuggestions.Feed.Network.RequestStatusCode",
                            status_code);

   // The below is true even if there is a protocol error, so this will
   // record response size as long as the request completed.
   if (status_code >= 200) {
     UMA_HISTOGRAM_COUNTS_1M("ContentSuggestions.Feed.Network.ResponseSizeKB",
                             static_cast<int>(response_body.size() / 1024));
   }

   std::move(done_callback_).Run(status_code, std::move(response_body));
 }

 FeedNetworkingHost::FeedNetworkingHost(
     signin::IdentityManager* identity_manager,
     const std::string& api_key,
     scoped_refptr<network::SharedURLLoaderFactory> loader_factory,
     const base::TickClock* tick_clock,
     PrefService* pref_service)
     : identity_manager_(identity_manager),
       api_key_(api_key),
       loader_factory_(std::move(loader_factory)),
       tick_clock_(tick_clock),
       pref_service_(pref_service) {}

 FeedNetworkingHost::~FeedNetworkingHost() = default;

 void FeedNetworkingHost::CancelRequests() {
   pending_requests_.clear();
 }

 void FeedNetworkingHost::Send(
     const GURL& url,
     const std::string& request_type,
     std::vector<uint8_t> request_body,
     ResponseCallback callback) {
   auto fetch = std::make_unique<NetworkFetch>(
       url, request_type, std::move(request_body), identity_manager_,
       loader_factory_.get(), api_key_, tick_clock_, pref_service_);
   NetworkFetch* fetch_unowned = fetch.get();
   pending_requests_.emplace(std::move(fetch));

   // It's safe to pass base::Unretained(this) since deleting the network fetch
   // will prevent the callback from being completed.
   fetch_unowned->Start(base::BindOnce(&FeedNetworkingHost::NetworkFetchFinished,
                                       base::Unretained(this), fetch_unowned,
                                       std::move(callback)));
 }

 void FeedNetworkingHost::NetworkFetchFinished(
     NetworkFetch* fetch,
     ResponseCallback callback,
     int32_t http_code,
     std::vector<uint8_t> response_body) {
   auto fetch_iterator = pending_requests_.find(fetch);
   CHECK(fetch_iterator != pending_requests_.end());
   pending_requests_.erase(fetch_iterator);

   std::move(callback).Run(http_code, std::move(response_body));
 }

 }  // namespace feed
	// Copyright 2018 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 "components/feed/core/feed_networking_host.h"

	#include <utility>

	#include "base/bind.h"
	#include "base/metrics/field_trial_params.h"
	#include "base/metrics/histogram_functions.h"
	#include "base/metrics/histogram_macros.h"
	#include "base/strings/stringprintf.h"
	#include "base/time/tick_clock.h"
	#include "base/time/time.h"
	#include "base/values.h"
	#include "components/feed/core/common/pref_names.h"
	#include "components/feed/feed_feature_list.h"
	#include "components/prefs/pref_service.h"
	#include "components/signin/public/identity_manager/access_token_info.h"
	#include "components/signin/public/identity_manager/identity_manager.h"
	#include "components/signin/public/identity_manager/primary_account_access_token_fetcher.h"
	#include "components/signin/public/identity_manager/scope_set.h"
	#include "components/variations/net/variations_http_headers.h"
	#include "google_apis/gaia/google_service_auth_error.h"
	#include "net/base/load_flags.h"
	#include "net/base/url_util.h"
	#include "net/http/http_response_headers.h"
	#include "net/http/http_status_code.h"
	#include "net/traffic_annotation/network_traffic_annotation.h"
	#include "services/network/public/cpp/resource_request.h"
	#include "services/network/public/cpp/resource_request_body.h"
	#include "services/network/public/cpp/shared_url_loader_factory.h"
	#include "services/network/public/cpp/simple_url_loader.h"
	#include "services/network/public/mojom/url_response_head.mojom.h"

	#include "third_party/zlib/google/compression_utils.h"

	using IdentityManager = signin::IdentityManager;

	namespace {

	constexpr char kApiKeyQueryParam[] = "key";
	constexpr char kAuthenticationScope[] =
	"https://www.googleapis.com/auth/googlenow";
	constexpr char kAuthorizationRequestHeaderFormat[] = "Bearer %s";

	constexpr char kContentEncoding[] = "Content-Encoding";
	constexpr char kContentType[] = "application/octet-stream";
	constexpr char kGzip[] = "gzip";

	} // namespace

	namespace feed {

	// NetworkFetch is a helper class internal to the networking host. Each
	// instance represents a single "logical" fetch that ends by calling the
	// associated callback. Network fetches will actually attempt two fetches if
	// there is a signed in user; the first to retrieve an access token, and the
	// second to the specified url.
	class NetworkFetch {
	public:
	NetworkFetch(const GURL& url,
	const std::string& request_type,
	std::vector<uint8_t> request_body,
	IdentityManager* identity_manager,
	network::SharedURLLoaderFactory* loader_factory,
	const std::string& api_key,
	const base::TickClock* tick_clock,
	PrefService* pref_service);

	void Start(FeedNetworkingHost::ResponseCallback done_callback);

	private:
	void StartAccessTokenFetch();
	void AccessTokenFetchFinished(base::TimeTicks token_start_ticks,
	GoogleServiceAuthError error,
	signin::AccessTokenInfo access_token_info);
	void StartLoader();
	std::unique_ptr<network::SimpleURLLoader> MakeLoader();
	void SetRequestHeaders(bool has_request_body,
	network::ResourceRequest* request) const;
	void PopulateRequestBody(network::SimpleURLLoader* loader);
	void OnSimpleLoaderComplete(std::unique_ptr<std::string> response);

	GURL url_;
	const std::string request_type_;
	std::string access_token_;
	const std::vector<uint8_t> request_body_;
	IdentityManager* const identity_manager_;
	std::unique_ptr<signin::PrimaryAccountAccessTokenFetcher> token_fetcher_;
	std::unique_ptr<network::SimpleURLLoader> simple_loader_;
	FeedNetworkingHost::ResponseCallback done_callback_;
	network::SharedURLLoaderFactory* loader_factory_;
	const std::string api_key_;
	const base::TickClock* tick_clock_;

	// Set when the NetworkFetch is constructed, before token and article fetch.
	const base::TimeTicks entire_send_start_ticks_;

	// Should be set right before the article fetch, and after the token fetch if
	// there is one.
	base::TimeTicks loader_only_start_ticks_;
	PrefService* pref_service_;
	bool host_overridden_ = false;

	DISALLOW_COPY_AND_ASSIGN(NetworkFetch);
	};

	NetworkFetch::NetworkFetch(const GURL& url,
	const std::string& request_type,
	std::vector<uint8_t> request_body,
	IdentityManager* identity_manager,
	network::SharedURLLoaderFactory* loader_factory,
	const std::string& api_key,
	const base::TickClock* tick_clock,
	PrefService* pref_service)
	: url_(url),
	request_type_(request_type),
	request_body_(std::move(request_body)),
	identity_manager_(identity_manager),
	loader_factory_(loader_factory),
	api_key_(api_key),
	tick_clock_(tick_clock),
	entire_send_start_ticks_(tick_clock_->NowTicks()),
	pref_service_(pref_service) {
	// Apply the host override (from snippets-internals).
	std::string host_override =
	pref_service_->GetString(feed::prefs::kHostOverrideHost);
	if (!host_override.empty()) {
	GURL override_host_url(host_override);
	if (override_host_url.is_valid()) {
	GURL::Replacements replacements;
	replacements.SetSchemeStr(override_host_url.scheme_piece());
	replacements.SetHostStr(override_host_url.host_piece());
	replacements.SetPortStr(override_host_url.port_piece());
	url_ = url_.ReplaceComponents(replacements);
	host_overridden_ = true;
	}
	}
	}

	void NetworkFetch::Start(FeedNetworkingHost::ResponseCallback done_callback) {
	done_callback_ = std::move(done_callback);

	if (!identity_manager_->HasPrimaryAccount()) {
	StartLoader();
	return;
	}

	StartAccessTokenFetch();
	}

	void NetworkFetch::StartAccessTokenFetch() {
	signin::ScopeSet scopes{kAuthenticationScope};
	// It's safe to pass base::Unretained(this) since deleting the token fetcher
	// will prevent the callback from being completed.
	token_fetcher_ = std::make_unique<signin::PrimaryAccountAccessTokenFetcher>(
	"feed", identity_manager_, scopes,
	base::BindOnce(&NetworkFetch::AccessTokenFetchFinished,
	base::Unretained(this), tick_clock_->NowTicks()),
	signin::PrimaryAccountAccessTokenFetcher::Mode::kWaitUntilAvailable);
	}

	void NetworkFetch::AccessTokenFetchFinished(
	base::TimeTicks token_start_ticks,
	GoogleServiceAuthError error,
	signin::AccessTokenInfo access_token_info) {
	UMA_HISTOGRAM_ENUMERATION("ContentSuggestions.Feed.Network.TokenFetchStatus",
	error.state(), GoogleServiceAuthError::NUM_STATES);

	base::TimeDelta token_duration = tick_clock_->NowTicks() - token_start_ticks;
	UMA_HISTOGRAM_MEDIUM_TIMES("ContentSuggestions.Feed.Network.TokenDuration",
	token_duration);

	access_token_ = access_token_info.token;
	StartLoader();
	}

	void NetworkFetch::StartLoader() {
	loader_only_start_ticks_ = tick_clock_->NowTicks();
	simple_loader_ = MakeLoader();
	simple_loader_->DownloadToStringOfUnboundedSizeUntilCrashAndDie(
	loader_factory_, base::BindOnce(&NetworkFetch::OnSimpleLoaderComplete,
	base::Unretained(this)));
	}

	std::unique_ptr<network::SimpleURLLoader> NetworkFetch::MakeLoader() {
	// TODO(pnoland): Add data use measurement once it's supported for simple
	// url loader.
	net::NetworkTrafficAnnotationTag traffic_annotation =
	net::DefineNetworkTrafficAnnotation("interest_feed_send", R"(
	semantics {
	sender: "Feed Library"
	description: "Chrome can show content suggestions (e.g. articles) "
	"in the form of a feed. For signed-in users, these may be "
	"personalized based on the user's synced browsing history."
	trigger: "Triggered periodically in the background, or upon "
	"explicit user request."
	data: "The locale of the device and data describing the suggested "
	"content that the user interacted with. For signed in users "
	"the request is authenticated. "
	destination: GOOGLE_OWNED_SERVICE
	}
	policy {
	cookies_allowed: YES
	cookies_store: "user"
	setting: "This can be disabled from the New Tab Page by collapsing "
	"the articles section."
	chrome_policy {
	NTPContentSuggestionsEnabled {
	policy_options {mode: MANDATORY}
	NTPContentSuggestionsEnabled: false
	}
	}
	})");
	GURL url(url_);
	if (access_token_.empty() && !api_key_.empty())
	url = net::AppendQueryParameter(url_, kApiKeyQueryParam, api_key_);

	auto resource_request = std::make_unique<network::ResourceRequest>();
	resource_request->url = url;

	resource_request->load_flags = net::LOAD_BYPASS_CACHE;
	resource_request->credentials_mode = network::mojom::CredentialsMode::kOmit;
	resource_request->method = request_type_;

	// Include credentials ONLY if the user has overridden the feed host through
	// the internals page. This allows for some authentication workflows we need
	// for testing.
	if (host_overridden_) {
	resource_request->credentials_mode =
	network::mojom::CredentialsMode::kInclude;
	resource_request->site_for_cookies = net::SiteForCookies::FromUrl(url);
	}

	SetRequestHeaders(!request_body_.empty(), resource_request.get());

	auto simple_loader = network::SimpleURLLoader::Create(
	std::move(resource_request), traffic_annotation);
	simple_loader->SetAllowHttpErrorResults(true);
	simple_loader->SetTimeoutDuration(
	base::TimeDelta::FromSeconds(kTimeoutDurationSeconds.Get()));
	PopulateRequestBody(simple_loader.get());
	return simple_loader;
	}

	void NetworkFetch::SetRequestHeaders(bool has_request_body,
	network::ResourceRequest* request) const {
	if (has_request_body) {
	request->headers.SetHeader(net::HttpRequestHeaders::kContentType,
	kContentType);
	request->headers.SetHeader(kContentEncoding, kGzip);
	}

	variations::SignedIn signed_in_status = variations::SignedIn::kNo;
	if (!access_token_.empty()) {
	std::string auth_header = base::StringPrintf(
	kAuthorizationRequestHeaderFormat, access_token_.c_str());
	request->headers.SetHeader(net::HttpRequestHeaders::kAuthorization,
	auth_header);
	signed_in_status = variations::SignedIn::kYes;
	}

	// Add X-Client-Data header with experiment IDs from field trials.
	variations::AppendVariationsHeader(url_, variations::InIncognito::kNo,
	signed_in_status, request);
	}

	void NetworkFetch::PopulateRequestBody(network::SimpleURLLoader* loader) {
	std::string compressed_request_body;
	if (!request_body_.empty()) {
	std::string uncompressed_request_body(
	reinterpret_cast<const char*>(request_body_.data()),
	request_body_.size());

	compression::GzipCompress(uncompressed_request_body,
	&compressed_request_body);

	loader->AttachStringForUpload(compressed_request_body, kContentType);
	}

	UMA_HISTOGRAM_COUNTS_1M(
	"ContentSuggestions.Feed.Network.RequestSizeKB.Compressed",
	static_cast<int>(compressed_request_body.size() / 1024));
	}

	void NetworkFetch::OnSimpleLoaderComplete(
	std::unique_ptr<std::string> response) {
	int32_t status_code = simple_loader_->NetError();
	// If overriding the feed host, try to grab the Bless nonce. This is
	// strictly informational, and only displayed in snippets-internals.
	if (host_overridden_ && simple_loader_->ResponseInfo()) {
	size_t iter = 0;
	std::string value;
	while (simple_loader_->ResponseInfo()->headers->EnumerateHeader(
	&iter, "www-authenticate", &value)) {
	size_t pos = value.find("nonce=\"");
	if (pos != std::string::npos) {
	std::string nonce = value.substr(pos + 7, 16);
	if (nonce.size() == 16) {
	pref_service_->SetString(feed::prefs::kHostOverrideBlessNonce, nonce);
	break;
	}
	}
	}
	}
	std::vector<uint8_t> response_body;

	if (response) {
	status_code = simple_loader_->ResponseInfo()->headers->response_code();

	if (status_code == net::HTTP_UNAUTHORIZED) {
	signin::ScopeSet scopes{kAuthenticationScope};
	CoreAccountId account_id = identity_manager_->GetPrimaryAccountId();
	if (!account_id.empty()) {
	identity_manager_->RemoveAccessTokenFromCache(account_id, scopes,
	access_token_);
	}
	}

	const uint8_t* begin = reinterpret_cast<const uint8_t*>(response->data());
	const uint8_t* end = begin + response->size();
	response_body.assign(begin, end);
	}

	base::TimeDelta entire_send_duration =
	tick_clock_->NowTicks() - entire_send_start_ticks_;
	UMA_HISTOGRAM_MEDIUM_TIMES("ContentSuggestions.Feed.Network.Duration",
	entire_send_duration);

	base::TimeDelta loader_only_duration =
	tick_clock_->NowTicks() - loader_only_start_ticks_;
	// This histogram purposefully matches name and bucket size used in
	// RemoteSuggestionsFetcherImpl.
	UMA_HISTOGRAM_TIMES("NewTabPage.Snippets.FetchTime", loader_only_duration);

	base::UmaHistogramSparse("ContentSuggestions.Feed.Network.RequestStatusCode",
	status_code);

	// The below is true even if there is a protocol error, so this will
	// record response size as long as the request completed.
	if (status_code >= 200) {
	UMA_HISTOGRAM_COUNTS_1M("ContentSuggestions.Feed.Network.ResponseSizeKB",
	static_cast<int>(response_body.size() / 1024));
	}

	std::move(done_callback_).Run(status_code, std::move(response_body));
	}

	FeedNetworkingHost::FeedNetworkingHost(
	signin::IdentityManager* identity_manager,
	const std::string& api_key,
	scoped_refptr<network::SharedURLLoaderFactory> loader_factory,
	const base::TickClock* tick_clock,
	PrefService* pref_service)
	: identity_manager_(identity_manager),
	api_key_(api_key),
	loader_factory_(std::move(loader_factory)),
	tick_clock_(tick_clock),
	pref_service_(pref_service) {}

	FeedNetworkingHost::~FeedNetworkingHost() = default;

	void FeedNetworkingHost::CancelRequests() {
	pending_requests_.clear();
	}

	void FeedNetworkingHost::Send(
	const GURL& url,
	const std::string& request_type,
	std::vector<uint8_t> request_body,
	ResponseCallback callback) {
	auto fetch = std::make_unique<NetworkFetch>(
	url, request_type, std::move(request_body), identity_manager_,
	loader_factory_.get(), api_key_, tick_clock_, pref_service_);
	NetworkFetch* fetch_unowned = fetch.get();
	pending_requests_.emplace(std::move(fetch));

	// It's safe to pass base::Unretained(this) since deleting the network fetch
	// will prevent the callback from being completed.
	fetch_unowned->Start(base::BindOnce(&FeedNetworkingHost::NetworkFetchFinished,
	base::Unretained(this), fetch_unowned,
	std::move(callback)));
	}

	void FeedNetworkingHost::NetworkFetchFinished(
	NetworkFetch* fetch,
	ResponseCallback callback,
	int32_t http_code,
	std::vector<uint8_t> response_body) {
	auto fetch_iterator = pending_requests_.find(fetch);
	CHECK(fetch_iterator != pending_requests_.end());
	pending_requests_.erase(fetch_iterator);

	std::move(callback).Run(http_code, std::move(response_body));
	}

	} // namespace feed