views: Mark single-argument constructors as explicit.

ui/views/controls/menu/native_menu_win.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 "ui/views/controls/menu/native_menu_win.h"
 
 #include <Windowsx.h>
 
 #include "base/bind.h"
 #include "base/logging.h"
@@ skipping 56 matching lines @@
   mi.cbSize = sizeof(mi);
   mi.fMask = MIM_MENUDATA | MIM_STYLE;
   GetMenuInfo(hmenu, &mi);
   return reinterpret_cast<NativeMenuWin*>(mi.dwMenuData);
 }
 
 // A window that receives messages from Windows relevant to the native menu
 // structure we have constructed in NativeMenuWin.
 class NativeMenuWin::MenuHostWindow {
  public:
-  MenuHostWindow(NativeMenuWin* parent) : parent_(parent) {
+  explicit MenuHostWindow(NativeMenuWin* parent) : parent_(parent) {
     RegisterClass();
     hwnd_ = CreateWindowEx(l10n_util::GetExtendedStyles(), kWindowClassName,
                            L"", 0, 0, 0, 0, 0, HWND_MESSAGE, NULL, NULL, NULL);
     ui::CheckWindowCreated(hwnd_);
     ui::SetWindowUserData(hwnd_, this);
   }
 
   ~MenuHostWindow() {
     DestroyWindow(hwnd_);
   }
@@ skipping 653 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // MenuWrapper, public:
 
 // static
 MenuWrapper* MenuWrapper::CreateWrapper(ui::MenuModel* model) {
   return new NativeMenuWin(model, NULL);
 }
 
 }  // namespace views