[Win] Update HWND style when SizeConstraintsChanged.

ui/views/widget/widget_hwnd_utils.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/widget/widget_hwnd_utils.h"
 
 #include <dwmapi.h>
 
 #include "base/command_line.h"
 #include "base/win/windows_version.h"
@@ skipping 63 matching lines @@
   // Set type-dependent style attributes.
   switch (params.type) {
     case Widget::InitParams::TYPE_PANEL:
       *ex_style |= WS_EX_TOPMOST;
       if (params.remove_standard_frame) {
         *style |= WS_POPUP;
         break;
       }
       // Else, no break. Fall through to TYPE_WINDOW.
     case Widget::InitParams::TYPE_WINDOW: {
-      *style |= WS_SYSMENU | WS_CAPTION;
-      bool can_resize = widget_delegate->CanResize();
-      bool can_maximize = widget_delegate->CanMaximize();
-      if (can_maximize) {
-        *style |= WS_OVERLAPPEDWINDOW;
-      } else if (can_resize || params.remove_standard_frame) {
-        *style |= WS_OVERLAPPED | WS_THICKFRAME;
-      }
+      // WS_OVERLAPPEDWINDOW is equivalent to:
+      //   WS_OVERLAPPED | WS_CAPTION | WS_SYSMENU |
+      //   WS_THICKFRAME | WS_MINIMIZEBOX | WS_MAXIMIZEBOX
+      *style |= WS_OVERLAPPEDWINDOW;
+      if (!widget_delegate->CanMaximize())
+        *style &= ~WS_MAXIMIZEBOX;
+      if (!widget_delegate->CanMinimize())
+        *style &= ~WS_MINIMIZEBOX;
+      if (!widget_delegate->CanResize())
+        *style &= ~(WS_THICKFRAME | WS_MAXIMIZEBOX);
+      if (params.remove_standard_frame)
+        *style &= ~(WS_MINIMIZEBOX | WS_MAXIMIZEBOX);
+
       if (native_widget_delegate->IsDialogBox()) {
         *style |= DS_MODALFRAME;
         // NOTE: Turning this off means we lose the close button, which is bad.
         // Turning it on though means the user can maximize or size the window
         // from the system menu, which is worse. We may need to provide our own
         // menu to get the close button to appear properly.
         // style &= ~WS_SYSMENU;
 
         // Set the WS_POPUP style for modal dialogs. This ensures that the owner
         // window is activated on destruction. This style should not be set for
@@ skipping 51 matching lines @@
   DWORD class_style = 0;
   CalculateWindowStylesFromInitParams(params, widget_delegate,
                                       native_widget_delegate, &style, &ex_style,
                                       &class_style);
   handler->set_initial_class_style(class_style);
   handler->set_window_style(handler->window_style() | style);
   handler->set_window_ex_style(handler->window_ex_style() | ex_style);
 }
 
 }  // namespace views