Fix window drawing after snap on Windows 10.

ui/views/win/hwnd_message_handler.h

 // 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.
 
 #ifndef UI_VIEWS_WIN_HWND_MESSAGE_HANDLER_H_
 #define UI_VIEWS_WIN_HWND_MESSAGE_HANDLER_H_
 
 #include <windows.h>
 
 #include <stddef.h>
@@ skipping 41 matching lines @@
 // with captions. They appear to paint the window caption and frame.
 // Unfortunately if you override the standard non-client rendering as we do
 // with CustomFrameWindow, sometimes Windows (not deterministically
 // reproducibly but definitely frequently) will send these messages to the
 // window and paint the standard caption/title over the top of the custom one.
 // So we need to handle these messages in CustomFrameWindow to prevent this
 // from happening.
 const int WM_NCUAHDRAWCAPTION = 0xAE;
 const int WM_NCUAHDRAWFRAME = 0xAF;
 
+// The HWNDMessageHandler sends this message to itself on
+// WM_WINDOWPOSCHANGING. It's used to inform the client if a
+// WM_WINDOWPOSCHANGED won't be received.
+const int WM_WINDOWSIZINGFINISHED = WM_USER;
+
 // IsMsgHandled() and BEGIN_SAFE_MSG_MAP_EX are a modified version of
 // BEGIN_MSG_MAP_EX. The main difference is it uses a WeakPtrFactory member
 // (|weak_factory|) that is used in _ProcessWindowMessage() and changing
 // IsMsgHandled() from a member function to a define that checks if the weak
 // factory is still valid in addition to the member. Together these allow for
 // |this| to be deleted during dispatch.
 #define IsMsgHandled() !ref.get() || msg_handled_
 
 #define BEGIN_SAFE_MSG_MAP_EX(weak_factory) \
  private: \
@@ skipping 294 matching lines @@
     CR_MESSAGE_HANDLER_EX(WM_CHAR, OnImeMessages)
     CR_MESSAGE_HANDLER_EX(WM_SYSCHAR, OnImeMessages)
 
     // Scroll events
     CR_MESSAGE_HANDLER_EX(WM_VSCROLL, OnScrollMessage)
     CR_MESSAGE_HANDLER_EX(WM_HSCROLL, OnScrollMessage)
 
     // Touch Events.
     CR_MESSAGE_HANDLER_EX(WM_TOUCH, OnTouchEvent)
 
+    CR_MESSAGE_HANDLER_EX(WM_WINDOWSIZINGFINISHED, OnWindowSizingFinished)
+
     // Uses the general handler macro since the specific handler macro
     // MSG_WM_NCACTIVATE would convert WPARAM type to BOOL type. The high
     // word of WPARAM could be set when the window is minimized or restored.
     CR_MESSAGE_HANDLER_EX(WM_NCACTIVATE, OnNCActivate)
 
     // This list is in _ALPHABETICAL_ order! OR I WILL HURT YOU.
     CR_MSG_WM_ACTIVATEAPP(OnActivateApp)
     CR_MSG_WM_APPCOMMAND(OnAppCommand)
     CR_MSG_WM_CANCELMODE(OnCancelMode)
     CR_MSG_WM_CAPTURECHANGED(OnCaptureChanged)
@@ skipping 77 matching lines @@
   void OnSetFocus(HWND last_focused_window);
   LRESULT OnSetIcon(UINT size_type, HICON new_icon);
   LRESULT OnSetText(const wchar_t* text);
   void OnSettingChange(UINT flags, const wchar_t* section);
   void OnSize(UINT param, const gfx::Size& size);
   void OnSysCommand(UINT notification_code, const gfx::Point& point);
   void OnThemeChanged();
   LRESULT OnTouchEvent(UINT message, WPARAM w_param, LPARAM l_param);
   void OnWindowPosChanging(WINDOWPOS* window_pos);
   void OnWindowPosChanged(WINDOWPOS* window_pos);
+  LRESULT OnWindowSizingFinished(UINT message, WPARAM w_param, LPARAM l_param);
 
   // Receives Windows Session Change notifications.
   void OnSessionChange(WPARAM status_code);
 
   typedef std::vector<ui::TouchEvent> TouchEvents;
   // Helper to handle the list of touch events passed in. We need this because
   // touch events on windows don't fire if we enter a modal loop in the context
   // of a touch event.
   void HandleTouchEvents(const TouchEvents& touch_events);
 
@@ skipping 152 matching lines @@
 
   // On Windows Vista and beyond, if we are transitioning from custom frame
   // to Aero(glass) we delay setting the DWM related properties in full
   // screen mode as DWM is not supported in full screen windows. We perform
   // the DWM related operations when the window comes out of fullscreen mode.
   // This member variable is set to true if the window is transitioning to
   // glass. Defaults to false.
   bool dwm_transition_desired_;
 
   // True if HandleWindowSizeChanging has been called in the delegate, but not
-  // HandleWindowSizeChanged.
+  // HandleClientSizeChanged.
   bool sent_window_size_changing_;
 
+  // This is used to keep track of whether a WM_WINDOWPOSCHANGED has
+  // been received after the WM_WINDOWPOSCHANGING.
+  uint32_t current_window_size_message_ = 0;
+
   // Manages observation of Windows Session Change messages.
   std::unique_ptr<WindowsSessionChangeObserver>
       windows_session_change_observer_;
 
   // This class provides functionality to register the legacy window as a
   // Direct Manipulation consumer. This allows us to support smooth scroll
   // in Chrome on Windows 10.
   std::unique_ptr<gfx::win::DirectManipulationHelper>
       direct_manipulation_helper_;
 
@@ skipping 26 matching lines @@
 
   // The factory used with BEGIN_SAFE_MSG_MAP_EX.
   base::WeakPtrFactory<HWNDMessageHandler> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(HWNDMessageHandler);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIN_HWND_MESSAGE_HANDLER_H_