Restore maximized window position after detaching display.

ui/views/win/hwnd_message_handler.cc

Index: ui/views/win/hwnd_message_handler.cc
diff --git a/ui/views/win/hwnd_message_handler.cc b/ui/views/win/hwnd_message_handler.cc
index ec631af3b840741db1404d454ad652586b11bc25..c20f120cb4af921dcecf891c05ec462d884be59d 100644
--- a/ui/views/win/hwnd_message_handler.cc
+++ b/ui/views/win/hwnd_message_handler.cc
@@ -1631,6 +1631,35 @@ LRESULT HWNDMessageHandler::OnPointerActivate(UINT message,
 
 void HWNDMessageHandler::OnMove(const gfx::Point& point) {
   delegate_->HandleMove();
+
+  RECT window_rect;

[sky, 2016/09/29 18:16:23]

Would it make more sense for this to be in OnWindowPosChanging?

+  HMONITOR monitor;
+  gfx::Rect monitor_rect, work_area;
+  if (!GetParent(hwnd()) && IsMaximized() &&
+      GetWindowRect(hwnd(), &window_rect) &&
+      GetMonitorAndRects(window_rect, &monitor, &monitor_rect, &work_area)) {
+    gfx::Rect expected_window_bounds = work_area;
+
+    // Windows automatically adds a standard width border to all sides when a
+    // window is maximized. We should take this into account.
+    gfx::Insets client_area_insets;
+    if (GetClientAreaInsets(&client_area_insets))
+      expected_window_bounds.Inset(client_area_insets.Scale(-1));
+
+    if (GetWindowBoundsInScreen() != expected_window_bounds) {
+      // Sometimes Windows incorrectly changes bounds of maximized windows after
+      // attaching or detaching additional displays. In this case user can see
+      // non-client area of the window (that should be hidden in normal case).
+      // This workaround code restores window position if problem occurs.
+      SetWindowPos(hwnd(), NULL,
+                   expected_window_bounds.x(),
+                   expected_window_bounds.y(),
+                   expected_window_bounds.width(),
+                   expected_window_bounds.height(),
+                   SWP_NOACTIVATE | SWP_NOZORDER);
+    }
+  }
+
   SetMsgHandled(FALSE);
 }