Fix the issue that a panel window cannot be shrink to very small

views/widget/native_widget_win.cc

Index: views/widget/native_widget_win.cc
===================================================================
--- views/widget/native_widget_win.cc	(revision 98900)
+++ views/widget/native_widget_win.cc	(working copy)
@@ -2024,6 +2024,18 @@
     window_pos->flags &= ~SWP_SHOWWINDOW;
   }
 
+  // When WM_WINDOWPOSCHANGING message is handled by DefWindowProc, it will
+  // enforce (cx, cy) not to be smaller than (6, 6) for any non-popup window.
+  // We work around this by changing cy back to our intended value.
+  if (!GetParent() && ~(window_pos->flags & SWP_NOSIZE) && window_pos->cy < 6) {
+    LONG old_cy = window_pos->cy;
+    DefWindowProc(GetNativeView(), WM_WINDOWPOSCHANGING, 0,
+        reinterpret_cast<LPARAM>(window_pos));
+    window_pos->cy = old_cy;
+    SetMsgHandled(TRUE);
+    return;
+  }
+
   SetMsgHandled(FALSE);
 }
 
@@ -2056,7 +2068,7 @@
 gfx::Insets NativeWidgetWin::GetClientAreaInsets() const {
   // Returning an empty Insets object causes the default handling in
   // NativeWidgetWin::OnNCCalcSize() to be invoked.
-  if (!GetWidget()->non_client_view() || GetWidget()->ShouldUseNativeFrame())
+  if (GetWidget()->ShouldUseNativeFrame())
     return gfx::Insets();
 
   if (IsMaximized()) {