Track printer protocol usage for CUPS printers.

chrome/browser/ui/webui/print_preview/printer_backend_proxy_chromeos.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/print_preview/printer_backend_proxy.h"
 
 #include <memory>
 #include <vector>
 
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/task_scheduler/post_task.h"
 #include "base/values.h"
 #include "chrome/browser/chromeos/printing/cups_print_job_manager.h"
 #include "chrome/browser/chromeos/printing/cups_print_job_manager_factory.h"
 #include "chrome/browser/chromeos/printing/ppd_provider_factory.h"
 #include "chrome/browser/chromeos/printing/printer_configurer.h"
 #include "chrome/browser/chromeos/printing/printers_manager.h"
 #include "chrome/browser/chromeos/printing/printers_manager_factory.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/webui/print_preview/printer_capabilities.h"
@@ skipping 92 matching lines @@
 
     std::unique_ptr<chromeos::Printer> printer =
         prefs_->GetPrinter(printer_name);
     if (!printer) {
       // If the printer was removed, the lookup will fail.
       content::BrowserThread::PostTask(content::BrowserThread::UI, FROM_HERE,
                                        base::Bind(cb, nullptr));
       return;
     }
 
+    // Log printer configuration for selected printer.
+    UMA_HISTOGRAM_ENUMERATION("CUPS.ProtocolUsed", printer->GetProtocol(),
+                              chromeos::Printer::PROTOCOL_MAX);

[Carlson, 2017/05/25 16:24:35]

Should we be leaving space in the enum for possible future values?

[skau, 2017/05/25 18:49:55]

No.  The max value is just to help in constructing the buckets locally.  We'll
just add values above PROTOCOL_MAX and it'll increment automatically.

+
     if (prefs_->IsConfigurationCurrent(*printer)) {
       // Skip setup if the printer is already installed.
       HandlePrinterSetup(std::move(printer), cb, chromeos::SUCCESS);
       return;
     }
 
     const chromeos::Printer& printer_ref = *printer;
     printer_configurer_->SetUpPrinter(
         printer_ref,
         base::Bind(&PrinterBackendProxyChromeos::HandlePrinterSetup,
@@ skipping 47 matching lines @@
 };
 
 }  // namespace
 
 std::unique_ptr<PrinterBackendProxy> PrinterBackendProxy::Create(
     Profile* profile) {
   return base::MakeUnique<PrinterBackendProxyChromeos>(profile);
 }
 
 }  // namespace printing