Cleanup: Fix some misc nits in printing code.

chrome/browser/printing/print_preview_dialog_controller_browsertest.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 "base/bind_helpers.h"
 #include "base/location.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/run_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 128 matching lines @@
       nullptr,
       GURL(kDummyPrintUrl),
       GURL(),
       &pdf_plugin_info));
 }
 
 }  // namespace
 
 class PrintPreviewDialogControllerBrowserTest : public InProcessBrowserTest {
  public:
-  PrintPreviewDialogControllerBrowserTest() : initiator_(NULL) {}
+  PrintPreviewDialogControllerBrowserTest() : initiator_(nullptr) {}
   ~PrintPreviewDialogControllerBrowserTest() override {}
 
   WebContents* initiator() {
     return initiator_;
   }
 
   void PrintPreview() {
     base::RunLoop run_loop;
     request_preview_dialog_observer()->set_quit_closure(run_loop.QuitClosure());
     chrome::Print(browser());
@@ skipping 23 matching lines @@
     initiator_ = browser()->tab_strip_model()->GetActiveWebContents();
     ASSERT_TRUE(initiator_);
     ASSERT_NE(first_tab, initiator_);
 
     content::PluginService::GetInstance()->Init();
     content::PluginService::GetInstance()->DisablePluginsDiscoveryForTesting();
   }
 
   void TearDownOnMainThread() override {
     cloned_tab_observer_.reset();
-    initiator_ = NULL;
+    initiator_ = nullptr;
   }
 
   RequestPrintPreviewObserver* request_preview_dialog_observer() {
     return cloned_tab_observer_->request_preview_dialog_observer();
   }
 
   scoped_ptr<PrintPreviewDialogClonedObserver> cloned_tab_observer_;
   WebContents* initiator_;
 
   DISALLOW_COPY_AND_ASSIGN(PrintPreviewDialogControllerBrowserTest);
@@ skipping 119 matching lines @@
 
     frame_count = 0;
     preview_dialog->ForEachFrame(
         base::Bind(&CountFrames, base::Unretained(&frame_count)));
   } while (frame_count < kExpectedFrameCount);
   ASSERT_EQ(kExpectedFrameCount, frame_count);
 
   // Make sure all the frames in the dialog has access to the PDF plugin.
   preview_dialog->ForEachFrame(base::Bind(&CheckPdfPluginForRenderFrame));
 }