Modernize code print_dialog_gtk.cc.

Use base::NoDestructor, range-based for loops, and initialize members in
headers. Also mark some constants as constexpr.

Change-Id: I7cfef2e80f8fc285af560f48cfbcaf264b03513e
Reviewed-on: https://chromium-review.googlesource.com/1189542Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586370}

chrome/browser/ui/libgtkui/print_dialog_gtk.cc

@@ -15,9 +15,9 @@
 
 #include "base/bind.h"
 #include "base/files/file_util.h"
-#include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/macros.h"
+#include "base/no_destructor.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/task/post_task.h"
 #include "base/values.h"
@@ -43,19 +43,19 @@ const char kDuplexTumble[] = "DuplexTumble";
 const char kDuplexNoTumble[] = "DuplexNoTumble";
 #endif
 
-int kPaperSizeTresholdMicrons = 100;
-int kMicronsInMm = 1000;
+constexpr int kPaperSizeTresholdMicrons = 100;
+constexpr int kMicronsInMm = 1000;
 
-// Checks whether gtk_paper_size can be used to represent user selected media.
+// Checks whether |gtk_paper_size| can be used to represent user selected media.
 // In fuzzy match mode checks that paper sizes are "close enough" (less than
 // 1mm difference). In the exact mode, looks for the paper with the same PPD
 // name and "close enough" size.
 bool PaperSizeMatch(GtkPaperSize* gtk_paper_size,
                     const PrintSettings::RequestedMedia& media,
                     bool fuzzy_match) {
-  if (!gtk_paper_size) {
+  if (!gtk_paper_size)
     return false;
-  }
+
   gfx::Size paper_size_microns(
       static_cast<int>(gtk_paper_size_get_width(gtk_paper_size, GTK_UNIT_MM) *
                            kMicronsInMm +
@@ -66,12 +66,12 @@ bool PaperSizeMatch(GtkPaperSize* gtk_paper_size,
   int diff = std::max(
       std::abs(paper_size_microns.width() - media.size_microns.width()),
       std::abs(paper_size_microns.height() - media.size_microns.height()));
-  if (fuzzy_match) {
-    return diff <= kPaperSizeTresholdMicrons;
-  }
-  return !media.vendor_id.empty() &&
-         media.vendor_id == gtk_paper_size_get_ppd_name(gtk_paper_size) &&
-         diff <= kPaperSizeTresholdMicrons;
+  bool close_enough = diff <= kPaperSizeTresholdMicrons;
+  if (fuzzy_match)
+    return close_enough;
+
+  return close_enough && !media.vendor_id.empty() &&
+         media.vendor_id == gtk_paper_size_get_ppd_name(gtk_paper_size);
 }
 
 // Looks up a paper size matching (in terms of PaperSizeMatch) the user selected
@@ -82,12 +82,11 @@ GtkPaperSize* FindPaperSizeMatch(GList* gtk_paper_sizes,
   GtkPaperSize* first_fuzzy_match = nullptr;
   for (GList* p = gtk_paper_sizes; p && p->data; p = g_list_next(p)) {
     GtkPaperSize* gtk_paper_size = static_cast<GtkPaperSize*>(p->data);
-    if (PaperSizeMatch(gtk_paper_size, media, false)) {
+    if (PaperSizeMatch(gtk_paper_size, media, false))
       return gtk_paper_size;
-    }
-    if (!first_fuzzy_match && PaperSizeMatch(gtk_paper_size, media, true)) {
+
+    if (!first_fuzzy_match && PaperSizeMatch(gtk_paper_size, media, true))
       first_fuzzy_match = gtk_paper_size;
-    }
   }
   return first_fuzzy_match;
 }
@@ -96,7 +95,7 @@ class StickyPrintSettingGtk {
  public:
   StickyPrintSettingGtk() : last_used_settings_(gtk_print_settings_new()) {}
   ~StickyPrintSettingGtk() {
-    NOTREACHED();  // Intended to be used with a Leaky LazyInstance.
+    NOTREACHED();  // Intended to be used with base::NoDestructor.
   }
 
   GtkPrintSettings* settings() { return last_used_settings_; }
@@ -113,21 +112,19 @@ class StickyPrintSettingGtk {
   DISALLOW_COPY_AND_ASSIGN(StickyPrintSettingGtk);
 };
 
-base::LazyInstance<StickyPrintSettingGtk>::Leaky g_last_used_settings =
-    LAZY_INSTANCE_INITIALIZER;
+StickyPrintSettingGtk& GetLastUsedSettings() {
+  static base::NoDestructor<StickyPrintSettingGtk> settings;
+  return *settings;
+}
 
 // Helper class to track GTK printers.
 class GtkPrinterList {
  public:
-  GtkPrinterList() : default_printer_(nullptr) {
-    gtk_enumerate_printers(SetPrinter, this, nullptr, TRUE);
-  }
+  GtkPrinterList() { gtk_enumerate_printers(SetPrinter, this, nullptr, TRUE); }
 
   ~GtkPrinterList() {
-    for (std::vector<GtkPrinter*>::iterator it = printers_.begin();
-         it < printers_.end(); ++it) {
-      g_object_unref(*it);
-    }
+    for (GtkPrinter* printer : printers_)
+      g_object_unref(printer);
   }
 
   // Can return nullptr if there's no default printer. E.g. Printer on a laptop
@@ -141,11 +138,9 @@ class GtkPrinterList {
     if (name.empty())
       return nullptr;
 
-    for (std::vector<GtkPrinter*>::iterator it = printers_.begin();
-         it < printers_.end(); ++it) {
-      if (gtk_printer_get_name(*it) == name) {
-        return *it;
-      }
+    for (GtkPrinter* printer : printers_) {
+      if (gtk_printer_get_name(printer) == name)
+        return printer;
     }
 
     return nullptr;
@@ -165,7 +160,7 @@ class GtkPrinterList {
   }
 
   std::vector<GtkPrinter*> printers_;
-  GtkPrinter* default_printer_;
+  GtkPrinter* default_printer_ = nullptr;
 };
 
 }  // namespace
@@ -178,12 +173,7 @@ printing::PrintDialogGtkInterface* PrintDialogGtk::CreatePrintDialog(
 }
 
 PrintDialogGtk::PrintDialogGtk(PrintingContextLinux* context)
-    : context_(context),
-      dialog_(nullptr),
-      gtk_settings_(nullptr),
-      page_setup_(nullptr),
-      printer_(nullptr),
-      parent_(nullptr) {}
+    : context_(context) {}
 
 PrintDialogGtk::~PrintDialogGtk() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
@@ -213,8 +203,7 @@ void PrintDialogGtk::UseDefaultSettings() {
   DCHECK(!printer_);
 
   // |gtk_settings_| is a new copy.
-  gtk_settings_ =
-      gtk_print_settings_copy(g_last_used_settings.Get().settings());
+  gtk_settings_ = gtk_print_settings_copy(GetLastUsedSettings().settings());
   page_setup_ = gtk_page_setup_new();
 
   PrintSettings settings;
@@ -222,10 +211,8 @@ void PrintDialogGtk::UseDefaultSettings() {
 }
 
 void PrintDialogGtk::UpdateSettings(printing::PrintSettings* settings) {
-  if (!gtk_settings_) {
-    gtk_settings_ =
-        gtk_print_settings_copy(g_last_used_settings.Get().settings());
-  }
+  if (!gtk_settings_)
+    gtk_settings_ = gtk_print_settings_copy(GetLastUsedSettings().settings());
 
   auto printer_list = std::make_unique<GtkPrinterList>();
   printer_ = printer_list->GetPrinterWithName(
@@ -319,7 +306,7 @@ void PrintDialogGtk::ShowDialog(
     bool has_selection,
     PrintingContextLinux::PrintSettingsCallback callback) {
   callback_ = std::move(callback);
-  DCHECK(!callback_.is_null());
+  DCHECK(callback_);
 
   dialog_ = gtk_print_unix_dialog_new(nullptr, nullptr);
   libgtkui::SetGtkTransientForAura(dialog_, parent_view);
@@ -504,7 +491,7 @@ void PrintDialogGtk::SendDocumentToPrinter(
   }
 
   // Save the settings for next time.
-  g_last_used_settings.Get().SetLastUsedSettings(gtk_settings_);
+  GetLastUsedSettings().SetLastUsedSettings(gtk_settings_);
 
   GtkPrintJob* print_job =
       gtk_print_job_new(base::UTF16ToUTF8(document_name).c_str(), printer_,
@@ -539,6 +526,6 @@ void PrintDialogGtk::OnWindowDestroying(aura::Window* window) {
   DCHECK_EQ(parent_, window);
   parent_ = nullptr;
   window->RemoveObserver(this);
-  if (!callback_.is_null())
+  if (callback_)
     std::move(callback_).Run(PrintingContextLinux::CANCEL);
 }

chrome/browser/ui/libgtkui/print_dialog_gtk.h

@@ -75,16 +75,16 @@ class PrintDialogGtk : public printing::PrintDialogGtkInterface,
 
   // Printing dialog callback.
   PrintingContextLinux::PrintSettingsCallback callback_;
-  PrintingContextLinux* context_;
+  PrintingContextLinux* const context_;
 
   // Print dialog settings. PrintDialogGtk owns |dialog_| and holds references
   // to the other objects.
-  GtkWidget* dialog_;
-  GtkPrintSettings* gtk_settings_;
-  GtkPageSetup* page_setup_;
-  GtkPrinter* printer_;
+  GtkWidget* dialog_ = nullptr;
+  GtkPrintSettings* gtk_settings_ = nullptr;
+  GtkPageSetup* page_setup_ = nullptr;
+  GtkPrinter* printer_ = nullptr;
 
-  aura::Window* parent_;
+  aura::Window* parent_ = nullptr;
 
   base::FilePath path_to_pdf_;