Add policy to use system default printer

chrome/browser/ui/webui/print_preview/print_preview_ui.cc

 // Copyright (c) 2012 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/print_preview_ui.h"
 
 #include <map>
 #include <utility>
 #include <vector>
 
+#include "base/command_line.h"
 #include "base/feature_list.h"
 #include "base/id_map.h"
 #include "base/lazy_instance.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/synchronization/lock.h"
 #include "base/values.h"
 #include "build/build_config.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/printing/background_printing_manager.h"
 #include "chrome/browser/printing/print_preview_data_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/webui/metrics_handler.h"
 #include "chrome/browser/ui/webui/print_preview/print_preview_handler.h"
 #include "chrome/browser/ui/webui/theme_source.h"
 #include "chrome/common/chrome_features.h"
+#include "chrome/common/chrome_switches.h"
+#include "chrome/common/pref_names.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/grit/browser_resources.h"
 #include "chrome/grit/chromium_strings.h"
 #include "chrome/grit/generated_resources.h"
+#include "components/prefs/pref_service.h"
 #include "components/printing/common/print_messages.h"
 #include "components/strings/grit/components_strings.h"
 #include "content/public/browser/url_data_source.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_ui_data_source.h"
 #include "extensions/common/constants.h"
 #include "printing/features/features.h"
 #include "printing/page_size_margins.h"
 #include "printing/print_job_constants.h"
 #include "ui/base/l10n/l10n_util.h"
@@ skipping 389 matching lines @@
     : ConstrainedWebDialogUI(web_ui),
       initial_preview_start_time_(base::TimeTicks::Now()),
       id_(g_print_preview_ui_id_map.Get().Add(this)),
       handler_(nullptr),
       source_is_modifiable_(true),
       source_has_selection_(false),
       print_selection_only_(false),
       dialog_closed_(false) {
   // Set up the chrome://print/ data source.
   Profile* profile = Profile::FromWebUI(web_ui);
-  content::WebUIDataSource::Add(profile, CreatePrintPreviewUISource());
+  content::WebUIDataSource* data_source = CreatePrintPreviewUISource();
+  const base::CommandLine* cmdline = base::CommandLine::ForCurrentProcess();
+  bool use_system_default_printer =
+      profile->GetPrefs()->GetBoolean(
+          prefs::kUseSystemDefaultPrinterAsDefault) ||
+      cmdline->HasSwitch(switches::kUseSystemDefaultPrinter);
+  data_source->AddBoolean("useSystemDefaultPrinter",

[Lei Zhang, 2017/06/15 18:29:34]

Can we do this in CreatePrintPreviewUISource()? Look in the bottom of that
method where we do similar things already.

[rbpotter, 2017/06/16 02:21:46]

Done.

+                          use_system_default_printer);
+  content::WebUIDataSource::Add(profile, data_source);
 
   // Set up the chrome://theme/ source.
   content::URLDataSource::Add(profile, new ThemeSource(profile));
 
   auto handler = base::MakeUnique<PrintPreviewHandler>();
   handler_ = handler.get();
   web_ui->AddMessageHandler(std::move(handler));
   web_ui->AddMessageHandler(base::MakeUnique<MetricsHandler>());
 
   g_print_preview_request_id_map.Get().Set(id_, -1);
@@ skipping 230 matching lines @@
 }
 
 void PrintPreviewUI::SetSelectedFileForTesting(const base::FilePath& path) {
   handler_->FileSelected(path, 0, NULL);
 }
 
 void PrintPreviewUI::SetPdfSavedClosureForTesting(
     const base::Closure& closure) {
   handler_->SetPdfSavedClosureForTesting(closure);
 }