Fix window drawing after snap on Windows 10.

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 <tchar.h>
@@ skipping 1085 matching lines @@
     TrackMouseEvents(mouse_tracking_flags);
   }
 }
 
 void HWNDMessageHandler::ClientAreaSizeChanged() {
   // Ignore size changes due to fullscreen windows losing activation.
   if (background_fullscreen_hack_ && !sent_window_size_changing_)
     return;
   gfx::Size s = GetClientAreaBounds().size();
   delegate_->HandleClientSizeChanged(s);
+
+  current_window_size_message_++;
+  sent_window_size_changing_ = false;
 }
 
 bool HWNDMessageHandler::GetClientAreaInsets(gfx::Insets* insets) const {
   if (delegate_->GetClientAreaInsets(insets))
     return true;
   DCHECK(insets->IsEmpty());
 
   // Returning false causes the default handling in OnNCCalcSize() to
   // be invoked.
   if (!delegate_->HasNonClientView() || HasSystemFrame())
@@ skipping 1151 matching lines @@
 
   RECT window_rect;
   gfx::Size old_size;
   if (GetWindowRect(hwnd(), &window_rect))
     old_size = gfx::Rect(window_rect).size();
   gfx::Size new_size = gfx::Size(window_pos->cx, window_pos->cy);
   if ((old_size != new_size && !(window_pos->flags & SWP_NOSIZE)) ||
       window_pos->flags & SWP_FRAMECHANGED) {
     delegate_->HandleWindowSizeChanging();
     sent_window_size_changing_ = true;
+
+    // It's possible that if Aero snap is being entered then the window size
+    // won't actually change. Post a message to ensure swaps will be re-enabled
+    // in that case.
+    PostMessage(hwnd(), WM_WINDOWSIZINGFINISHED, ++current_window_size_message_,
+                0);
   }
 
   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);
@@ skipping 13 matching lines @@
   if (window_pos->flags & SWP_SHOWWINDOW) {
     delegate_->HandleVisibilityChanged(true);
     if (direct_manipulation_helper_)
       direct_manipulation_helper_->Activate(hwnd());
     SetDwmFrameExtension(DwmFrameState::ON);
   } else if (window_pos->flags & SWP_HIDEWINDOW) {
     delegate_->HandleVisibilityChanged(false);
     if (direct_manipulation_helper_)
       direct_manipulation_helper_->Deactivate(hwnd());
   }
-  if (sent_window_size_changing_) {
-    sent_window_size_changing_ = false;
-    delegate_->HandleWindowSizeChanged();
-  }
+
   SetMsgHandled(FALSE);
 }
 
+LRESULT HWNDMessageHandler::OnWindowSizingFinished(UINT message,
+                                                   WPARAM w_param,
+                                                   LPARAM l_param) {
+  // Check if a newer WM_WINDOWPOSCHANGING or WM_WINDOWPOSCHANGED have been
+  // received after this message was posted.
+  if (current_window_size_message_ != w_param)
+    return 0;
+
+  delegate_->HandleWindowSizeUnchanged();
+  sent_window_size_changing_ = false;
+

[sky, 2016/08/01 15:30:09]

SetMsgHanded(FALSE)?

+  return 0;
+}
+
 void HWNDMessageHandler::OnSessionChange(WPARAM status_code) {
   // Direct3D presents are ignored while the screen is locked, so force the
   // window to be redrawn on unlock.
   if (status_code == WTS_SESSION_UNLOCK)
     ForceRedrawWindow(10);
 }
 
 void HWNDMessageHandler::HandleTouchEvents(const TouchEvents& touch_events) {
   base::WeakPtr<HWNDMessageHandler> ref(weak_factory_.GetWeakPtr());
   for (size_t i = 0; i < touch_events.size() && ref; ++i)
@@ skipping 344 matching lines @@
   MONITORINFO monitor_info = {sizeof(monitor_info)};
   GetMonitorInfo(MonitorFromWindow(hwnd(), MONITOR_DEFAULTTOPRIMARY),
                  &monitor_info);
   gfx::Rect shrunk_rect(monitor_info.rcMonitor);
   shrunk_rect.set_height(shrunk_rect.height() - 1);
   background_fullscreen_hack_ = true;
   SetBoundsInternal(shrunk_rect, false);
 }
 
 }  // namespace views