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 020d0a1f9e06a46b1e80c081bb01d338c22a004e..6f80d3e568e2ca1dc1471d563356f850ec2bdc39 100644
--- a/ui/views/win/hwnd_message_handler.cc
+++ b/ui/views/win/hwnd_message_handler.cc
@@ -2227,12 +2227,47 @@ void HWNDMessageHandler::OnWindowPosChanging(WINDOWPOS* window_pos) {
     }
   } else if (!GetParent(hwnd())) {
     RECT window_rect;
+    const bool have_new_window_rect =
+        !(window_pos->flags & SWP_NOMOVE) && !(window_pos->flags & SWP_NOSIZE);
+    if (have_new_window_rect) {
+      // We should use new window rect for detecting monitor and it's
+      // parameters, if it is available. If we use |GetWindowRect()| instead,
+      // we can break our same monitor detection logic (see |same_monitor|
+      // below) and consequently Windows "Move to other monitor" shortcuts
+      // (Win+Shift+Arrows). See crbug.com/656001.
+      window_rect.left = window_pos->x;
+      window_rect.top = window_pos->y;
+      window_rect.right = window_pos->x + window_pos->cx - 1;
+      window_rect.bottom = window_pos->y + window_pos->cy - 1;
+    }
+
     HMONITOR monitor;
     gfx::Rect monitor_rect, work_area;
-    if (GetWindowRect(hwnd(), &window_rect) &&
+    if ((have_new_window_rect || GetWindowRect(hwnd(), &window_rect)) &&
         GetMonitorAndRects(window_rect, &monitor, &monitor_rect, &work_area)) {
       bool work_area_changed = (monitor_rect == last_monitor_rect_) &&
                                (work_area != last_work_area_);
+      const bool same_monitor = monitor && (monitor == last_monitor_);
+
+      gfx::Rect expected_maximized_bounds = work_area;
+      if (IsMaximized()) {
+        // Windows automatically adds a standard width border to all sides when
+        // window is maximized. We should take this into account.
+        gfx::Insets client_area_insets;
+        if (GetClientAreaInsets(&client_area_insets))
+          expected_maximized_bounds.Inset(client_area_insets.Scale(-1));
+      }
+      // 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).
+      // We should restore window position if problem occurs.
+      const bool incorrect_maximized_bounds =
+          IsMaximized() && have_new_window_rect &&
+          (expected_maximized_bounds.x() != window_pos->x ||
+           expected_maximized_bounds.y() != window_pos->y ||
+           expected_maximized_bounds.width() != window_pos->cx ||
+           expected_maximized_bounds.height() != window_pos->cy);
+
       // If the size of a background fullscreen window changes again, then we
       // should reset the |background_fullscreen_hack_| flag.
       if (background_fullscreen_hack_ &&
@@ -2240,8 +2275,11 @@ void HWNDMessageHandler::OnWindowPosChanging(WINDOWPOS* window_pos) {
             (monitor_rect.height() - window_pos->cy != 1))) {
           background_fullscreen_hack_ = false;
       }
-      if (monitor && (monitor == last_monitor_) &&
-          ((IsFullscreen() && !background_fullscreen_hack_) ||
+      const bool fullscreen_without_hack =
+          IsFullscreen() && !background_fullscreen_hack_;
+
+      if (same_monitor &&
+          (incorrect_maximized_bounds || fullscreen_without_hack ||
            work_area_changed)) {
         // A rect for the monitor we're on changed.  Normally Windows notifies
         // us about this (and thus we're reaching here due to the SetWindowPos()
@@ -2255,9 +2293,7 @@ void HWNDMessageHandler::OnWindowPosChanging(WINDOWPOS* window_pos) {
         if (IsFullscreen()) {
           new_window_rect = monitor_rect;
         } else if (IsMaximized()) {
-          new_window_rect = work_area;
-          int border_thickness = GetSystemMetrics(SM_CXSIZEFRAME);
-          new_window_rect.Inset(-border_thickness, -border_thickness);
+          new_window_rect = expected_maximized_bounds;
         } else {
           new_window_rect = gfx::Rect(window_rect);
           new_window_rect.AdjustToFit(work_area);