scanning: Create metric to track scan job success rate

Create metric to track the scan job success rate of scans initiated from
the Scan app. This metric will not include canceled scans.

Bug: 1059779
Change-Id: I5487f643169fcffdfb7c50b074daed19bcd14d5e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2583211Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Reviewed-by: Jesse Schettler <jschettler@chromium.org>
Commit-Queue: Gavin Williams <gavinwill@chromium.org>
Cr-Commit-Position: refs/heads/master@{#836168}

chrome/browser/chromeos/scanning/scan_service.cc

@@ -12,6 +12,7 @@
 #include "base/check.h"
 #include "base/files/file_util.h"
 #include "base/location.h"
+#include "base/metrics/histogram_functions.h"
 #include "base/sequenced_task_runner.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
@@ -214,6 +215,11 @@ base::FilePath SavePage(const base::FilePath& scan_to_path,
   return scan_to_path.Append(filename);
 }
 
+// Records the histogram for scan job success.
+void RecordScanJobResult(bool success) {
+  base::UmaHistogramBoolean("Scanning.ScanJobSuccessful", success);
+}
+
 }  // namespace
 
 ScanService::ScanService(LorgnetteScannerManager* lorgnette_scanner_manager,
@@ -259,6 +265,7 @@ void ScanService::StartScan(
   const std::string scanner_name = GetScannerName(scanner_id);
   if (scanner_name.empty() || !FilePathSupported(settings->scan_to_path)) {
     std::move(callback).Run(false);
+    RecordScanJobResult(false);
     return;
   }
 
@@ -394,6 +401,7 @@ void ScanService::OnAllPagesSaved(bool success) {
     last_scanned_file_path_.clear();
 
   scan_job_observer_->OnScanComplete(!save_failed_, last_scanned_file_path_);
+  RecordScanJobResult(!save_failed_);
 }
 
 bool ScanService::FilePathSupported(const base::FilePath& file_path) {

tools/metrics/histograms/histograms_xml/scanning/histograms.xml

@@ -31,6 +31,17 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
   </summary>
 </histogram>
 
+<histogram name="Scanning.ScanJobSuccessful" enum="Boolean"
+    expires_after="2021-12-04">
+  <owner>gavinwill@chromium.org</owner>
+  <owner>cros-peripherals@google.com</owner>
+  <summary>
+    Records true if the attempted scan job completed successfully and false if
+    the scan job failed for any reason. This metric will not include canceled
+    scan jobs.
+  </summary>
+</histogram>
+
 </histograms>
 
 </histogram-configuration>