Do FinishAllRendering in WM_WINDOWPOSCHANGING

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 2206 matching lines @@
             FROM_HERE,
             base::Bind(&HWNDMessageHandler::StopIgnoringPosChanges,
                        weak_factory_.GetWeakPtr()));
       }
       last_monitor_ = monitor;
       last_monitor_rect_ = monitor_rect;
       last_work_area_ = work_area;
     }
   }
 
+  if (DidClientAreaSizeChange(window_pos))
+    delegate_->HandleWindowSizeChanging();
+
   if (ScopedFullscreenVisibility::IsHiddenForFullscreen(hwnd())) {
     // Prevent the window from being made visible if we've been asked to do so.
     // See comment in header as to why we might want this.
     window_pos->flags &= ~SWP_SHOWWINDOW;
   }
 
   if (window_pos->flags & SWP_SHOWWINDOW)
     delegate_->HandleVisibilityChanging(true);
   else if (window_pos->flags & SWP_HIDEWINDOW)
     delegate_->HandleVisibilityChanging(false);
@@ skipping 171 matching lines @@
     POINT cursor_pos = {0};
     ::GetCursorPos(&cursor_pos);
     if (memcmp(&cursor_pos, &mouse_location, sizeof(POINT)))
       return false;
     return true;
   }
   return false;
 }
 
 }  // namespace views