Fix black titlebar rendering when toggling DWM when the window is maximized:...

chrome/views/widget_win.h

 // Copyright (c) 2006-2008 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.
 
 #ifndef CHROME_VIEWS_WIDGET_WIN_H_
 #define CHROME_VIEWS_WIDGET_WIN_H_
 
 #include <atlbase.h>
 #include <atlcrack.h>
 
@@ skipping 226 matching lines @@
     MSG_WM_RBUTTONUP(OnRButtonUp)
     MSG_WM_SETCURSOR(OnSetCursor)
     MSG_WM_SETFOCUS(OnSetFocus)
     MSG_WM_SETICON(OnSetIcon)
     MSG_WM_SETTEXT(OnSetText)
     MSG_WM_SETTINGCHANGE(OnSettingChange)
     MSG_WM_SIZE(OnSize)
     MSG_WM_SYSCOMMAND(OnSysCommand)
     MSG_WM_THEMECHANGED(OnThemeChanged)
     MSG_WM_VSCROLL(OnVScroll)
+    MSG_WM_WINDOWPOSCHANGING(OnWindowPosChanging)
     MSG_WM_WINDOWPOSCHANGED(OnWindowPosChanged)
   END_MSG_MAP()
 
   // Overridden from Widget:
   virtual void GetBounds(gfx::Rect* out, bool including_frame) const;
   virtual void MoveToFront(bool should_activate);
   virtual HWND GetHWND() const;
   virtual void PaintNow(const gfx::Rect& update_rect);
   virtual RootView* GetRootView();
   virtual bool IsVisible();
@@ skipping 212 matching lines @@
     SetMsgHandled(FALSE);
     return 0;
   }
   virtual void OnSettingChange(UINT flags, const wchar_t* section);
   virtual void OnSize(UINT param, const CSize& size);
   virtual void OnSysCommand(UINT notification_code, CPoint click) { }
   virtual void OnThemeChanged();
   virtual void OnVScroll(int scroll_type, short position, HWND scrollbar) {
     SetMsgHandled(FALSE);
   }
+  virtual void OnWindowPosChanging(WINDOWPOS* window_pos) {
+    SetMsgHandled(FALSE);
+  }
   virtual void OnWindowPosChanged(WINDOWPOS* window_pos) {
     SetMsgHandled(FALSE);
   }
 
   // deletes this window as it is destroyed, override to provide different
   // behavior.
   virtual void OnFinalMessage(HWND window);
 
   // Start tracking all mouse events so that this window gets sent mouse leave
   // messages too. |is_nonclient| is true when we should track WM_NCMOUSELEAVE
@@ skipping 133 matching lines @@
   // Instance of accessibility information and handling for MSAA root
   CComPtr<IAccessible> accessibility_root_;
 
   // Our hwnd.
   HWND hwnd_;
 };
 
 }  // namespace views
 
 #endif  // #ifndef CHROME_VIEWS_WIDGET_WIN_H_