Migrate components/update_client/url_fetcher_downloader.cc

URLFetcher will stop working with advent of Network Service, and
SimpleURLLoader is the replacement API for most clients.
This CL migrates UrlFetcherDownloader away from URLFetcher.

Note that UrlFetcherDownloader makes use of URLFetcher's "progress
update" hook, in order to track fetch progresses. It turns out the
progress values were not being used in production at all:

UrlFetcherDownloader::OnURLFetchDownloadProgress used to instantiate
a CrxDownloader::Result object, and pass it all the way to
Component::StateDownloadingDiff::DownloadComplete and
Component::StateDownloading::DownloadComplete. There, |result|
parameter was being ignored in both methods.

Given SimpleURLLoader's lack of ability to hook to a progress update
callback at the time of doing this migration, and that the progress values
were not being used in production code anyways, this CL replaces
URLFetcher's progress upload hook by SimpleURLLoader's "response started"
hook, to indicate that the load has been triggered, and update
Component's status accordingly.

Hence, references to |CrxDownloader::Result::downloaded_bytes| and
|CrxDownloader::Result::total_bytes| were removed from CrxDownloaderTest.*
(components/update_client/crx_downloader_unittest.cc).

On the other hand, references to CrxDownloader::DownloadMetrics::downloaded_bytes
and |CrxDownloader::DownloadMetrics::total_bytes| remain unchanged
(update_client::BuildDownloadCompleteEventElement uses them).

Bug:844972,871211

Cq-Include-Trybots: luci.chromium.try:linux_mojo
Change-Id: I50410b46576263aec9a9a4b648a8a627f4832702
Reviewed-on: https://chromium-review.googlesource.com/1160725Reviewed-by: Matt Menke <mmenke@chromium.org>
Reviewed-by: Joshua Pawlicki <waffles@chromium.org>
Commit-Queue: Antonio Gomes <tonikitoo@igalia.com>
Cr-Commit-Position: refs/heads/master@{#582150}

components/update_client/BUILD.gn

@@ -177,6 +177,8 @@ source_set("unit_tests") {
     "//components/version_info:version_info",
     "//courgette:courgette_lib",
     "//net:test_support",
+    "//services/network:test_support",
+    "//services/network/public/cpp:cpp",
     "//services/network/public/cpp:cpp_base",
     "//services/service_manager/public/cpp",
     "//services/service_manager/public/cpp/test:test_support",

components/update_client/component.cc

@@ -507,7 +507,7 @@ void Component::StateDownloadingDiff::DoHandle() {
 
   crx_downloader_ = update_context.crx_downloader_factory(
       component.CanDoBackgroundDownload(),
-      update_context.config->RequestContext());
+      update_context.config->URLLoaderFactory());
 
   const auto& id = component.id_;
   crx_downloader_->set_progress_callback(
@@ -576,7 +576,7 @@ void Component::StateDownloading::DoHandle() {
 
   crx_downloader_ = update_context.crx_downloader_factory(
       component.CanDoBackgroundDownload(),
-      update_context.config->RequestContext());
+      update_context.config->URLLoaderFactory());
 
   const auto& id = component.id_;
   crx_downloader_->set_progress_callback(

components/update_client/crx_downloader.cc

@@ -21,7 +21,7 @@
 #include "components/update_client/update_client_errors.h"
 #include "components/update_client/url_fetcher_downloader.h"
 #include "components/update_client/utils.h"
-#include "net/url_request/url_request_context_getter.h"
+#include "services/network/public/cpp/shared_url_loader_factory.h"
 
 namespace update_client {
 
@@ -41,9 +41,10 @@ CrxDownloader::DownloadMetrics::DownloadMetrics()
 // which uses the BITS service.
 std::unique_ptr<CrxDownloader> CrxDownloader::Create(
     bool is_background_download,
-    scoped_refptr<net::URLRequestContextGetter> context_getter) {
+    scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
   std::unique_ptr<CrxDownloader> url_fetcher_downloader =
-      std::make_unique<UrlFetcherDownloader>(nullptr, context_getter);
+      std::make_unique<UrlFetcherDownloader>(nullptr,
+                                             std::move(url_loader_factory));
 
 #if defined(OS_WIN)
   if (is_background_download) {

components/update_client/crx_downloader.h

@@ -19,9 +19,8 @@
 #include "base/threading/thread_checker.h"
 #include "url/gurl.h"
 
-
-namespace net {
-class URLRequestContextGetter;
+namespace network {
+class SharedURLLoaderFactory;
 }
 
 namespace update_client {
@@ -65,6 +64,8 @@ class CrxDownloader {
     // Path of the downloaded file if the download was successful.
     base::FilePath response;
 
+    // TODO(crbug.com/871211): These values are not being used in production
+    // code. Clean it up.
     // Number of bytes actually downloaded, not including the bytes downloaded
     // as a result of falling back on urls.
     int64_t downloaded_bytes;
@@ -88,7 +89,7 @@ class CrxDownloader {
 
   using Factory = std::unique_ptr<CrxDownloader> (*)(
       bool,
-      scoped_refptr<net::URLRequestContextGetter>);
+      scoped_refptr<network::SharedURLLoaderFactory>);
 
   // Factory method to create an instance of this class and build the
   // chain of responsibility. |is_background_download| specifies that a
@@ -97,7 +98,7 @@ class CrxDownloader {
   // code such as file IO operations.
   static std::unique_ptr<CrxDownloader> Create(
       bool is_background_download,
-      scoped_refptr<net::URLRequestContextGetter> context_getter);
+      scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory);
   virtual ~CrxDownloader();
 
   void set_progress_callback(const ProgressCallback& progress_callback);

components/update_client/update_client_unittest.cc

@@ -278,7 +278,7 @@ TEST_F(UpdateClientTest, OneCrxNoUpdate) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 
@@ -443,7 +443,7 @@ TEST_F(UpdateClientTest, TwoCrxUpdateNoUpdate) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 
@@ -646,7 +646,7 @@ TEST_F(UpdateClientTest, TwoCrxUpdateFirstServerIgnoresSecond) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 
@@ -858,7 +858,7 @@ TEST_F(UpdateClientTest, TwoCrxUpdateNoCrxComponentData) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 
@@ -1001,7 +1001,7 @@ TEST_F(UpdateClientTest, TwoCrxUpdateNoCrxComponentDataAtAll) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 
@@ -1191,7 +1191,7 @@ TEST_F(UpdateClientTest, TwoCrxUpdateDownloadTimeout) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 
@@ -1486,7 +1486,7 @@ TEST_F(UpdateClientTest, OneCrxDiffUpdate) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 
@@ -1764,7 +1764,7 @@ TEST_F(UpdateClientTest, OneCrxInstallError) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 
@@ -2015,7 +2015,7 @@ TEST_F(UpdateClientTest, OneCrxDiffUpdateFailsFullUpdateSucceeds) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 
@@ -2240,7 +2240,7 @@ TEST_F(UpdateClientTest, OneCrxNoUpdateQueuedCall) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 
@@ -2388,7 +2388,7 @@ TEST_F(UpdateClientTest, OneCrxInstall) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 
@@ -2520,7 +2520,7 @@ TEST_F(UpdateClientTest, OneCrxInstallNoCrxComponentData) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 
@@ -2641,7 +2641,7 @@ TEST_F(UpdateClientTest, ConcurrentInstallSameCRX) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 
@@ -2731,7 +2731,7 @@ TEST_F(UpdateClientTest, EmptyIdList) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 
@@ -2792,7 +2792,7 @@ TEST_F(UpdateClientTest, SendUninstallPing) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return nullptr;
     }
 
@@ -2924,7 +2924,7 @@ TEST_F(UpdateClientTest, RetryAfter) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 
@@ -3167,7 +3167,7 @@ TEST_F(UpdateClientTest, TwoCrxUpdateOneUpdateDisabled) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 
@@ -3338,7 +3338,7 @@ TEST_F(UpdateClientTest, OneCrxUpdateCheckFails) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 
@@ -3485,7 +3485,7 @@ TEST_F(UpdateClientTest, OneCrxErrorUnknownApp) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 
@@ -3669,7 +3669,7 @@ TEST_F(UpdateClientTest, ActionRun_Install) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 
@@ -3816,7 +3816,7 @@ TEST_F(UpdateClientTest, ActionRun_NoUpdate) {
    public:
     static std::unique_ptr<CrxDownloader> Create(
         bool is_background_download,
-        scoped_refptr<net::URLRequestContextGetter> context_getter) {
+        scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
       return std::make_unique<MockCrxDownloader>();
     }
 

components/update_client/url_fetcher_downloader.cc

@@ -18,8 +18,9 @@
 #include "components/update_client/utils.h"
 #include "net/base/load_flags.h"
 #include "net/traffic_annotation/network_traffic_annotation.h"
-#include "net/url_request/url_fetcher.h"
-#include "net/url_request/url_request_context_getter.h"
+#include "services/network/public/cpp/resource_response.h"
+#include "services/network/public/cpp/shared_url_loader_factory.h"
+#include "services/network/public/cpp/simple_url_loader.h"
 #include "url/gurl.h"
 
 namespace {
@@ -32,32 +33,11 @@ constexpr base::TaskTraits kTaskTraits = {
 
 namespace update_client {
 
-UrlFetcherDownloader::URLFetcherDelegate::URLFetcherDelegate(
-    UrlFetcherDownloader* downloader)
-    : downloader_(downloader) {}
-
-UrlFetcherDownloader::URLFetcherDelegate::~URLFetcherDelegate() = default;
-
-void UrlFetcherDownloader::URLFetcherDelegate::OnURLFetchComplete(
-    const net::URLFetcher* source) {
-  downloader_->OnURLFetchComplete(source);
-}
-
-void UrlFetcherDownloader::URLFetcherDelegate::OnURLFetchDownloadProgress(
-    const net::URLFetcher* source,
-    int64_t current,
-    int64_t total,
-    int64_t current_network_bytes) {
-  downloader_->OnURLFetchDownloadProgress(source, current, total,
-                                          current_network_bytes);
-}
-
 UrlFetcherDownloader::UrlFetcherDownloader(
     std::unique_ptr<CrxDownloader> successor,
-    scoped_refptr<net::URLRequestContextGetter> context_getter)
+    scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory)
     : CrxDownloader(std::move(successor)),
-      delegate_(std::make_unique<URLFetcherDelegate>(this)),
-      context_getter_(context_getter) {}
+      url_loader_factory_(std::move(url_loader_factory)) {}
 
 UrlFetcherDownloader::~UrlFetcherDownloader() {
   DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
@@ -114,15 +94,13 @@ void UrlFetcherDownloader::StartURLFetch(const GURL& url) {
   if (download_dir_.empty()) {
     Result result;
     result.error = -1;
-    result.downloaded_bytes = downloaded_bytes_;
-    result.total_bytes = total_bytes_;
 
     DownloadMetrics download_metrics;
     download_metrics.url = url;
     download_metrics.downloader = DownloadMetrics::kUrlFetcher;
     download_metrics.error = -1;
-    download_metrics.downloaded_bytes = downloaded_bytes_;
-    download_metrics.total_bytes = total_bytes_;
+    download_metrics.downloaded_bytes = -1;
+    download_metrics.total_bytes = -1;
     download_metrics.download_time_ms = 0;
 
     main_task_runner()->PostTask(
@@ -134,27 +112,37 @@ void UrlFetcherDownloader::StartURLFetch(const GURL& url) {
 
   const base::FilePath response =
       download_dir_.AppendASCII(url.ExtractFileName());
-
-  url_fetcher_ = net::URLFetcher::Create(0, url, net::URLFetcher::GET,
-                                         delegate_.get(), traffic_annotation);
-  url_fetcher_->SetRequestContext(context_getter_.get());
-  url_fetcher_->SetLoadFlags(net::LOAD_DO_NOT_SEND_COOKIES |
-                             net::LOAD_DO_NOT_SAVE_COOKIES |
-                             net::LOAD_DISABLE_CACHE);
-  url_fetcher_->SetAutomaticallyRetryOn5xx(false);
-  url_fetcher_->SetAutomaticallyRetryOnNetworkChanges(3);
-  url_fetcher_->SaveResponseToFileAtPath(
-      response, base::CreateSequencedTaskRunnerWithTraits(kTaskTraits));
-  data_use_measurement::DataUseUserData::AttachToFetcher(
-      url_fetcher_.get(), data_use_measurement::DataUseUserData::UPDATE_CLIENT);
+  auto resource_request = std::make_unique<network::ResourceRequest>();
+  resource_request->url = url;
+  resource_request->load_flags = net::LOAD_DO_NOT_SEND_COOKIES |
+                                 net::LOAD_DO_NOT_SAVE_COOKIES |
+                                 net::LOAD_DISABLE_CACHE;
+  url_loader_ = network::SimpleURLLoader::Create(std::move(resource_request),
+                                                 traffic_annotation);
+  const int kMaxRetries = 3;
+  url_loader_->SetRetryOptions(
+      kMaxRetries,
+      network::SimpleURLLoader::RetryMode::RETRY_ON_NETWORK_CHANGE);
+
+  url_loader_->SetOnResponseStartedCallback(base::BindOnce(
+      &UrlFetcherDownloader::OnResponseStarted, base::Unretained(this)));
+
+  // For the end-to-end system it is important that the client reports the
+  // number of bytes it loaded from the server even in the case that the
+  // overall network transaction failed.
+  url_loader_->SetAllowPartialResults(true);
 
   VLOG(1) << "Starting background download: " << url.spec();
-  url_fetcher_->Start();
+  url_loader_->DownloadToFile(
+      url_loader_factory_.get(),
+      base::BindOnce(&UrlFetcherDownloader::OnURLLoadComplete,
+                     base::Unretained(this)),
+      response);
 
   download_start_time_ = base::TimeTicks::Now();
 }
 
-void UrlFetcherDownloader::OnURLFetchComplete(const net::URLFetcher* source) {
+void UrlFetcherDownloader::OnURLLoadComplete(base::FilePath file_path) {
   DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
 
   const base::TimeTicks download_end_time(base::TimeTicks::Now());
@@ -166,28 +154,44 @@ void UrlFetcherDownloader::OnURLFetchComplete(const net::URLFetcher* source) {
   // Consider a 5xx response from the server as an indication to terminate
   // the request and avoid overloading the server in this case.
   // is not accepting requests for the moment.
-  const int fetch_error(GetFetchError(*url_fetcher_));
+  int response_code = -1;
+  if (url_loader_->ResponseInfo() && url_loader_->ResponseInfo()->headers) {
+    response_code = url_loader_->ResponseInfo()->headers->response_code();
+  }
+
+  int fetch_error = -1;
+  if (!file_path.empty() && response_code == 200) {
+    fetch_error = 0;
+  } else if (response_code != -1) {
+    fetch_error = response_code;
+  } else {
+    fetch_error = url_loader_->NetError();
+  }
+
   const bool is_handled = fetch_error == 0 || IsHttpServerError(fetch_error);
 
   Result result;
   result.error = fetch_error;
   if (!fetch_error) {
-    source->GetResponseAsFilePath(true, &result.response);
+    result.response = file_path;
   }
-  result.downloaded_bytes = downloaded_bytes_;
-  result.total_bytes = total_bytes_;
 
   DownloadMetrics download_metrics;
   download_metrics.url = url();
   download_metrics.downloader = DownloadMetrics::kUrlFetcher;
   download_metrics.error = fetch_error;
-  download_metrics.downloaded_bytes = downloaded_bytes_;
+  // Tests expected -1, in case of failures and no content is available.
+  download_metrics.downloaded_bytes =
+      fetch_error && !url_loader_->GetContentSize()
+          ? -1
+          : url_loader_->GetContentSize();
   download_metrics.total_bytes = total_bytes_;
   download_metrics.download_time_ms = download_time.InMilliseconds();
 
-  VLOG(1) << "Downloaded " << downloaded_bytes_ << " bytes in "
+  VLOG(1) << "Downloaded " << url_loader_->GetContentSize() << " bytes in "
           << download_time.InMilliseconds() << "ms from "
-          << source->GetURL().spec() << " to " << result.response.value();
+          << url_loader_->GetFinalURL().spec() << " to "
+          << result.response.value();
 
   // Delete the download directory in the error cases.
   if (fetch_error && !download_dir_.empty())
@@ -201,21 +205,18 @@ void UrlFetcherDownloader::OnURLFetchComplete(const net::URLFetcher* source) {
                                 download_metrics));
 }
 
-void UrlFetcherDownloader::OnURLFetchDownloadProgress(
-    const net::URLFetcher* source,
-    int64_t current,
-    int64_t total,
-    int64_t current_network_bytes) {
+// This callback is used to indicate that a download has been started.
+void UrlFetcherDownloader::OnResponseStarted(
+    const GURL& final_url,
+    const network::ResourceResponseHead& response_head) {
   DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
 
-  downloaded_bytes_ = current;
-  total_bytes_ = total;
-
-  Result result;
-  result.downloaded_bytes = downloaded_bytes_;
-  result.total_bytes = total_bytes_;
+  if (response_head.content_length != -1)
+    total_bytes_ = response_head.content_length;
 
-  OnDownloadProgress(result);
+  // TODO(crbug.com/871211): |Result| is not being used on production.
+  // Clean it up.
+  OnDownloadProgress(Result());
 }
 
 }  // namespace update_client

components/update_client/url_fetcher_downloader.h

@@ -15,65 +15,42 @@
 #include "base/threading/thread_checker.h"
 #include "base/time/time.h"
 #include "components/update_client/crx_downloader.h"
-#include "net/url_request/url_fetcher_delegate.h"
 
-namespace net {
-class URLFetcher;
-class URLRequestContextGetter;
-}
+namespace network {
+class SharedURLLoaderFactory;
+class SimpleURLLoader;
+struct ResourceResponseHead;
+}  // namespace network
 
 namespace update_client {
 
-// Implements a CRX downloader in top of the URLFetcher.
+// Implements a CRX downloader in top of the SimpleURLLoader.
 class UrlFetcherDownloader : public CrxDownloader {
  public:
   UrlFetcherDownloader(
       std::unique_ptr<CrxDownloader> successor,
-      scoped_refptr<net::URLRequestContextGetter> context_getter);
+      scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory);
   ~UrlFetcherDownloader() override;
 
  private:
-  class URLFetcherDelegate : public net::URLFetcherDelegate {
-   public:
-    explicit URLFetcherDelegate(UrlFetcherDownloader* downloader);
-    ~URLFetcherDelegate() override;
-
-   private:
-    // Overrides for URLFetcherDelegate.
-    void OnURLFetchComplete(const net::URLFetcher* source) override;
-    void OnURLFetchDownloadProgress(const net::URLFetcher* source,
-                                    int64_t current,
-                                    int64_t total,
-                                    int64_t current_network_bytes) override;
-    // Not owned by this class.
-    UrlFetcherDownloader* downloader_ = nullptr;
-    DISALLOW_COPY_AND_ASSIGN(URLFetcherDelegate);
-  };
-
   // Overrides for CrxDownloader.
   void DoStartDownload(const GURL& url) override;
 
   void CreateDownloadDir();
   void StartURLFetch(const GURL& url);
-  void OnURLFetchComplete(const net::URLFetcher* source);
-  void OnURLFetchDownloadProgress(const net::URLFetcher* source,
-                                  int64_t current,
-                                  int64_t total,
-                                  int64_t current_network_bytes);
-
+  void OnURLLoadComplete(base::FilePath file_path);
+  void OnResponseStarted(const GURL& final_url,
+                         const network::ResourceResponseHead& response_head);
   THREAD_CHECKER(thread_checker_);
 
-  std::unique_ptr<URLFetcherDelegate> delegate_;
-
-  std::unique_ptr<net::URLFetcher> url_fetcher_;
-  scoped_refptr<net::URLRequestContextGetter> context_getter_;
+  scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory_;
+  std::unique_ptr<network::SimpleURLLoader> url_loader_;
 
   // Contains a temporary download directory for the downloaded file.
   base::FilePath download_dir_;
 
   base::TimeTicks download_start_time_;
 
-  int64_t downloaded_bytes_ = -1;
   int64_t total_bytes_ = -1;
 
   DISALLOW_COPY_AND_ASSIGN(UrlFetcherDownloader);