Run clang-modernize -use-nullptr over src/extensions/.

extensions/browser/app_window/app_window.cc

 // Copyright 2014 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 "extensions/browser/app_window/app_window.h"
 
 #include <algorithm>
 #include <string>
 #include <vector>
 
@@ skipping 424 matching lines @@
            delayed_show_type_ == SHOW_INACTIVE);
     Show(delayed_show_type_);
   }
 }
 
 void AppWindow::OnNativeClose() {
   AppWindowRegistry::Get(browser_context_)->RemoveAppWindow(this);
   if (app_window_contents_) {
     WebContents* web_contents = app_window_contents_->GetWebContents();
     WebContentsModalDialogManager::FromWebContents(web_contents)
-        ->SetDelegate(NULL);
+        ->SetDelegate(nullptr);
     app_window_contents_->NativeWindowClosed();
   }
   delete this;
 }
 
 void AppWindow::OnNativeWindowChanged() {
   SaveWindowPosition();
 
 #if defined(OS_WIN)
   if (native_app_window_ && cached_always_on_top_ && !IsFullscreen() &&
@@ skipping 610 matching lines @@
         region.bounds.x(),
         region.bounds.y(),
         region.bounds.right(),
         region.bounds.bottom(),
         region.draggable ? SkRegion::kUnion_Op : SkRegion::kDifference_Op);
   }
   return sk_region;
 }
 
 }  // namespace extensions