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

extensions/shell/browser/shell_desktop_controller.cc

Index: extensions/shell/browser/shell_desktop_controller.cc
diff --git a/extensions/shell/browser/shell_desktop_controller.cc b/extensions/shell/browser/shell_desktop_controller.cc
index 6e68087c22e409a2dd5936a9a45f6ebc3aa63fb5..78c753354020865d451ccd9b9a8a2bd7af266f4d 100644
--- a/extensions/shell/browser/shell_desktop_controller.cc
+++ b/extensions/shell/browser/shell_desktop_controller.cc
@@ -160,7 +160,7 @@ class AppsFocusRules : public wm::BaseFocusRules {
 }  // namespace
 
 ShellDesktopController::ShellDesktopController()
-    : app_window_client_(new ShellAppWindowClient), app_window_(NULL) {
+    : app_window_client_(new ShellAppWindowClient), app_window_(nullptr) {
   extensions::AppWindowClient::Set(app_window_client_.get());
 
 #if defined(OS_CHROMEOS)
@@ -181,7 +181,7 @@ ShellDesktopController::~ShellDesktopController() {
   chromeos::DBusThreadManager::Get()->GetPowerManagerClient()->
       RemoveObserver(this);
 #endif
-  extensions::AppWindowClient::Set(NULL);
+  extensions::AppWindowClient::Set(nullptr);
 }
 
 aura::WindowTreeHost* ShellDesktopController::GetHost() {
@@ -203,7 +203,7 @@ void ShellDesktopController::AddAppWindow(aura::Window* window) {
 void ShellDesktopController::CloseAppWindows() {
   if (app_window_) {
     app_window_->GetBaseWindow()->Close();  // Close() deletes |app_window_|.
-    app_window_ = NULL;
+    app_window_ = nullptr;
   }
 }
 
@@ -322,7 +322,7 @@ void ShellDesktopController::DestroyRootWindow() {
       static_cast<wm::FocusController*>(focus_client_.get());
   if (focus_controller) {
     host_->window()->RemovePreTargetHandler(focus_controller);
-    aura::client::SetActivationClient(host_->window(), NULL);
+    aura::client::SetActivationClient(host_->window(), nullptr);
   }
   root_window_event_filter_.reset();
   capture_client_.reset();