Make |DesktopWindowTreeHostX11::use_native_frame_| more robust. In particular,...

Make |DesktopWindowTreeHostX11::use_native_frame_| more robust. In particular, this CL ensures that widgets which expect to use the native frame (e.g. v2 apps, task manager) continue to do so even if DesktopWindowTreeHostX11::FrameTypeChanged() is called.

BUG=348437
TEST=None

Review URL: https://codereview.chromium.org/278823004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@271986 0039d316-1c4b-4281-b951-d872f2087c98

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc

@@ -628,6 +628,12 @@ bool DesktopWindowTreeHostX11::ShouldWindowContentsBeTransparent() const {
 void DesktopWindowTreeHostX11::FrameTypeChanged() {
   Widget::FrameType new_type =
       native_widget_delegate_->AsWidget()->frame_type();
+  if (new_type == Widget::FRAME_TYPE_DEFAULT) {
+    // The default is determined by Widget::InitParams::remove_standard_frame
+    // and does not change.
+    return;
+  }
+
   SetUseNativeFrame(new_type == Widget::FRAME_TYPE_FORCE_NATIVE);
   // Replace the frame and layout the contents. Even though we don't have a
   // swapable glass frame like on Windows, we still replace the frame because