Add metrics to printer setup flow.

chrome/browser/ui/webui/settings/chromeos/cups_printers_handler.cc

 // Copyright 2016 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/ui/webui/settings/chromeos/cups_printers_handler.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/files/file_util.h"
 #include "base/json/json_string_value_serializer.h"
 #include "base/memory/ptr_util.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/path_service.h"
 #include "base/strings/string_util.h"
 #include "base/threading/sequenced_task_runner_handle.h"
 #include "base/values.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chromeos/printing/ppd_provider_factory.h"
 #include "chrome/browser/chromeos/printing/printer_configurer.h"
 #include "chrome/browser/chromeos/printing/printer_discoverer.h"
 #include "chrome/browser/chromeos/printing/printers_manager_factory.h"
 #include "chrome/browser/download/download_prefs.h"
@@ skipping 13 matching lines @@
 #include "net/base/filename_util.h"
 #include "net/url_request/url_request_context_getter.h"
 #include "printing/backend/print_backend.h"
 #include "url/third_party/mozilla/url_parse.h"
 
 namespace chromeos {
 namespace settings {
 
 namespace {
 
+// These values are written to logs.  New enum values can be added, but existing
+// enums must never be renumbered or deleted and reused.
+enum PpdSourceForHistogram { kUser = 0, kScs = 1, kPpdSourceMax };
+
+void RecordPpdSource(const PpdSourceForHistogram& source) {
+  UMA_HISTOGRAM_ENUMERATION("Printing.CUPS.PpdSource", kUser, kPpdSourceMax);
+}
+
 void OnRemovedPrinter(bool success) {}
 
 std::unique_ptr<base::DictionaryValue> GetPrinterInfo(const Printer& printer) {
   std::unique_ptr<base::DictionaryValue> printer_info =
       base::MakeUnique<base::DictionaryValue>();
   printer_info->SetString("printerId", printer.id());
   printer_info->SetString("printerName", printer.display_name());
   printer_info->SetString("printerDescription", printer.description());
   printer_info->SetString("printerManufacturer", printer.manufacturer());
   printer_info->SetString("printerModel", printer.model());
@@ skipping 161 matching lines @@
 
   std::unique_ptr<Printer> printer = base::MakeUnique<Printer>(printer_id);
   printer->set_display_name(printer_name);
   printer->set_description(printer_description);
   printer->set_manufacturer(printer_manufacturer);
   printer->set_model(printer_model);
   printer->set_uri(printer_uri);
 
   // Verify a valid ppd path is present.
   if (!printer_ppd_path.empty()) {
+    RecordPpdSource(kUser);
     GURL tmp = net::FilePathToFileURL(base::FilePath(printer_ppd_path));
     if (!tmp.is_valid()) {
       LOG(ERROR) << "Invalid ppd path: " << printer_ppd_path;
       OnAddPrinterError();
       return;
     }
     printer->mutable_ppd_reference()->user_supplied_ppd_url = tmp.spec();
   } else if (!printer_manufacturer.empty() && !printer_model.empty()) {
+    RecordPpdSource(kScs);
     // Using the manufacturer and model, get a ppd reference.
     if (!ppd_provider_->GetPpdReference(printer_manufacturer, printer_model,
                                         printer->mutable_ppd_reference())) {
       LOG(ERROR) << "Failed to get ppd reference";
       OnAddPrinterError();
       return;
     }
   }
 
   // Copy the printer for the configurer.  Ownership needs to be transfered to
   // the receiver of the callback.
   const Printer printer_copy = *printer;
   printer_configurer_->SetUpPrinter(
       printer_copy,
       base::Bind(&CupsPrintersHandler::OnAddedPrinter,
                  weak_factory_.GetWeakPtr(), base::Passed(&printer)));
 }
 
 void CupsPrintersHandler::OnAddedPrinter(
     std::unique_ptr<Printer> printer,
     chromeos::PrinterSetupResult result_code) {
   std::string printer_name = printer->display_name();
+  UMA_HISTOGRAM_ENUMERATION("Printing.CUPS.PrinterSetupResult", result_code,
+                            chromeos::PrinterSetupResult::kMaxValue);
   switch (result_code) {
     case chromeos::PrinterSetupResult::kSuccess: {
       auto* manager = PrintersManagerFactory::GetForBrowserContext(profile_);
       manager->PrinterInstalled(*printer);
       manager->RegisterPrinter(std::move(printer));
       break;
     }
     case chromeos::PrinterSetupResult::kPpdNotFound:
       LOG(WARNING) << "Could not locate requested PPD";
       break;
@@ skipping 132 matching lines @@
 }
 
 void CupsPrintersHandler::OnPrintersFound(
     const std::vector<Printer>& printers) {
   std::unique_ptr<base::ListValue> printers_list =
       base::MakeUnique<base::ListValue>();
   for (const auto& printer : printers) {
     printers_list->Append(GetPrinterInfo(printer));
   }
 
+  UMA_HISTOGRAM_COUNTS_100("Printing.CUPS.PrintersDiscovered",

[Carlson, 2017/05/26 16:58:38]

Since this is potentially incremental, Would  it be better to record this in
OnDiscoveryInitialScanDone()? It's not clear to me that incremental results here
are useful things to record.

[skau, 2017/05/26 17:18:02]

I forgot this is incremental.  You're right that recording the incremental
values will throw off our counts.  Is there a way to get a count after the scan
is done?  We don't seem to store the whole list.

[Carlson, 2017/05/26 17:29:19]

It's incremental, but not in the way you're thinking, I think.  :)

This can be called multiple times, but each time it is called it gets the full
list of discovered printers to-date, obsoleting any previous received list.

That's why I was suggesting OnDiscoveryInitialScanDone() as a better place to do
this.  You'll have to stash the size of the most recent printers_list in the
object to make it work, but it's not too hacky, I think.

+                           printers_list->GetSize());
+
   FireWebUIListener("on-printer-discovered", *printers_list);
 }
 
 void CupsPrintersHandler::OnDiscoveryInitialScanDone() {
   FireWebUIListener("on-printer-discovery-done");
 }
 
 }  // namespace settings
 }  // namespace chromeos