Add WindowPinType property on arua::Window

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc

Index: ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
diff --git a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
index 4215122ffade7a990eb415818647160b0d436829..d966db428fccbc43179eb3cf798146ab6f148286 100644
--- a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
+++ b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
@@ -879,6 +879,12 @@ void DesktopWindowTreeHostX11::Minimize() {
   XIconifyWindow(xdisplay_, xwindow_, 0);
 }
 
+void DesktopWindowTreeHostX11::Pin(bool trusted) {
+  // We only use Pin() for ARC++ window on Chromebook, so we don't need
+  // implement it for X11.
+  NOTIMPLEMENTED();
+}
+
 void DesktopWindowTreeHostX11::Restore() {
   should_maximize_after_map_ = false;
   SetWMSpecState(false,
@@ -897,6 +903,10 @@ bool DesktopWindowTreeHostX11::IsMinimized() const {
   return HasWMSpecProperty("_NET_WM_STATE_HIDDEN");
 }
 
+bool DesktopWindowTreeHostX11::IsPinned() const {
+  return false;
+}
+
 bool DesktopWindowTreeHostX11::HasCapture() const {
   return g_current_capture == this;
 }