Add Download.IOSDownloadedFileNetError to New Download Manager.

This is an existing histogram logged for the Old Download Manager.
The histogram is already a part of histograms.xml file.

Bug: 791806
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I720221f6a5b395d947a96a99ce7e4d6fe7bee09e
Reviewed-on: https://chromium-review.googlesource.com/979267Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Commit-Queue: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#545722}

ios/chrome/browser/ui/download/download_manager_coordinator.mm

@@ -7,6 +7,7 @@
 #include <memory>
 
 #import "base/logging.h"
+#include "base/metrics/histogram_functions.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/user_metrics.h"
 #include "base/metrics/user_metrics_action.h"
@@ -49,6 +50,10 @@ class UnopenedDownloadsTracker : public web::DownloadTaskObserver {
                                     ? DownloadFileResult::Failure
                                     : DownloadFileResult::Completed,
                                 DownloadFileResult::Count);
+      if (task->GetErrorCode()) {
+        base::UmaHistogramSparse("Download.IOSDownloadedFileNetError",
+                                 -task->GetErrorCode());
+      }
     }
   }
   void OnDownloadDestroyed(web::DownloadTask* task) override {

ios/chrome/browser/ui/download/download_manager_coordinator_unittest.mm

@@ -407,6 +407,7 @@ TEST_F(DownloadManagerCoordinatorTest, OpenIn) {
 
   // Download task is destroyed without opening the file.
   task = nullptr;
+  histogram_tester_.ExpectTotalCount("Download.IOSDownloadedFileNetError", 0);
   histogram_tester_.ExpectUniqueSample(
       "Download.IOSDownloadFileResult",
       static_cast<base::HistogramBase::Sample>(DownloadFileResult::Completed),
@@ -444,6 +445,7 @@ TEST_F(DownloadManagerCoordinatorTest, DestroyInProgressDownload) {
 
   // Download task is destroyed before the download is complete.
   task = nullptr;
+  histogram_tester_.ExpectTotalCount("Download.IOSDownloadedFileNetError", 0);
   histogram_tester_.ExpectTotalCount("Download.IOSDownloadedFileAction", 0);
   histogram_tester_.ExpectUniqueSample(
       "Download.IOSDownloadFileResult",
@@ -499,6 +501,7 @@ TEST_F(DownloadManagerCoordinatorTest, OpenInDrive) {
         willBeginSendingToApplication:kGoogleDriveAppBundleID];
   }
 
+  histogram_tester_.ExpectTotalCount("Download.IOSDownloadedFileNetError", 0);
   histogram_tester_.ExpectTotalCount("Download.IOSDownloadFileResult", 0);
   histogram_tester_.ExpectUniqueSample("Download.IOSDownloadedFileAction",
                                        static_cast<base::HistogramBase::Sample>(
@@ -555,6 +558,7 @@ TEST_F(DownloadManagerCoordinatorTest, OpenInOtherApp) {
         willBeginSendingToApplication:@"foo-app-id"];
   }
 
+  histogram_tester_.ExpectTotalCount("Download.IOSDownloadedFileNetError", 0);
   histogram_tester_.ExpectTotalCount("Download.IOSDownloadFileResult", 0);
   histogram_tester_.ExpectUniqueSample(
       "Download.IOSDownloadedFileAction",
@@ -744,6 +748,8 @@ TEST_F(DownloadManagerCoordinatorTest, RetryingDownload) {
     return task_ptr->GetState() == web::DownloadTask::State::kInProgress;
   }));
 
+  histogram_tester_.ExpectUniqueSample("Download.IOSDownloadedFileNetError",
+                                       -net::ERR_INTERNET_DISCONNECTED, 1);
   histogram_tester_.ExpectUniqueSample(
       "Download.IOSDownloadFileResult",
       static_cast<base::HistogramBase::Sample>(DownloadFileResult::Failure), 1);