[Win] Update HWND style when SizeConstraintsChanged.

ui/views/win/hwnd_message_handler.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/win/hwnd_message_handler.h"
 
 #include <dwmapi.h>
 #include <oleacc.h>
 #include <shellapi.h>
 #include <wtsapi32.h>
@@ skipping 850 matching lines @@
 }
 
 void HWNDMessageHandler::SetFullscreen(bool fullscreen) {
   fullscreen_handler()->SetFullscreen(fullscreen);
   // If we are out of fullscreen and there was a pending DWM transition for the
   // window, then go ahead and do it now.
   if (!fullscreen && dwm_transition_desired_)
     PerformDwmTransition();
 }
 
+void HWNDMessageHandler::SizeConstraintsChanged() {
+  bool can_resize = delegate_->CanResize();
+  bool can_maximize = delegate_->CanMaximize();
+  LONG style = GetWindowLong(hwnd(), GWL_STYLE);
+  if (can_resize && can_maximize) {
+    style |= WS_MINIMIZEBOX | WS_MAXIMIZEBOX;
+  } else {
+    style &= ~(WS_MINIMIZEBOX | WS_MAXIMIZEBOX);
+  }
+  if (can_resize) {
+    style |= WS_THICKFRAME;
+  } else {
+    style &= ~WS_THICKFRAME;
+  }
+  SetWindowLong(hwnd(), GWL_STYLE, style);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // HWNDMessageHandler, InputMethodDelegate implementation:
 
 void HWNDMessageHandler::DispatchKeyEventPostIME(const ui::KeyEvent& key) {
   SetMsgHandled(delegate_->HandleKeyEvent(key));
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // HWNDMessageHandler, gfx::WindowImpl overrides:
 
@@ skipping 1579 matching lines @@
     SetWindowPos(hwnd(), NULL, 0, 0, 0, 0, flags | SWP_HIDEWINDOW);
     SetWindowPos(hwnd(), NULL, 0, 0, 0, 0, flags | SWP_SHOWWINDOW);
   }
   // WM_DWMCOMPOSITIONCHANGED is only sent to top level windows, however we want
   // to notify our children too, since we can have MDI child windows who need to
   // update their appearance.
   EnumChildWindows(hwnd(), &SendDwmCompositionChanged, NULL);
 }
 
 }  // namespace views