Cleanup: Fix some misc nits in printing code.

chrome/browser/printing/print_preview_context_menu_observer.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/printing/print_preview_context_menu_observer.h"
 
 #include "base/logging.h"
 #include "chrome/app/chrome_command_ids.h"
 #include "chrome/browser/printing/print_preview_dialog_controller.h"
 
 PrintPreviewContextMenuObserver::PrintPreviewContextMenuObserver(
     content::WebContents* contents) : contents_(contents) {
 }
 
 PrintPreviewContextMenuObserver::~PrintPreviewContextMenuObserver() {
 }
 
 bool PrintPreviewContextMenuObserver::IsPrintPreviewDialog() {
   printing::PrintPreviewDialogController* controller =
       printing::PrintPreviewDialogController::GetInstance();
   if (!controller)
     return false;
-  return (controller->GetPrintPreviewForContents(contents_) != NULL);
+  return (controller->GetPrintPreviewForContents(contents_) != nullptr);
 }
 
 bool PrintPreviewContextMenuObserver::IsCommandIdSupported(int command_id) {
   switch (command_id) {
     case IDC_PRINT:
     case IDC_VIEW_SOURCE:
     case IDC_CONTENT_CONTEXT_VIEWFRAMESOURCE:
     case IDC_CONTENT_CONTEXT_VIEWPAGEINFO:
     case IDC_CONTENT_CONTEXT_SEARCHWEBFOR:
       return IsPrintPreviewDialog();
@@ skipping 10 matching lines @@
     case IDC_CONTENT_CONTEXT_VIEWFRAMESOURCE:
     case IDC_CONTENT_CONTEXT_VIEWPAGEINFO:
     case IDC_CONTENT_CONTEXT_SEARCHWEBFOR:
       return false;
 
     default:
       NOTREACHED();
       return true;
   }
 }