Fix unfullscreening a maximized window in Metacity

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h"
 
 #include <X11/extensions/shape.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/Xatom.h>
 #include <X11/Xregion.h>
@@ skipping 664 matching lines @@
   // 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
   // the button assets don't update otherwise.
   native_widget_delegate_->AsWidget()->non_client_view()->UpdateFrame();
 }
 
 void DesktopWindowTreeHostX11::SetFullscreen(bool fullscreen) {
   if (is_fullscreen_ == fullscreen)
     return;
   is_fullscreen_ = fullscreen;
+
+  // Work around a bug where if we try to unfullscreen, metacity immediately
+  // fullscreens us again. This is a little flickery and not necessary if
+  // there's a gnome-panel, but it's not easy to detect whether there's a
+  // panel or not.
+  bool unmaximize_and_remaximize = !fullscreen && IsMaximized() &&
+                                   ui::GuessWindowManager() == ui::WM_METACITY;
+
+  if (unmaximize_and_remaximize)
+    Restore();
   SetWMSpecState(fullscreen,
                  atom_cache_.GetAtom("_NET_WM_STATE_FULLSCREEN"),
                  None);
+  if (unmaximize_and_remaximize)
+    Maximize();
+
   // Try to guess the size we will have after the switch to/from fullscreen:
   // - (may) avoid transient states
   // - works around Flash content which expects to have the size updated
   //   synchronously.
   // See https://crbug.com/361408
   if (fullscreen) {
     restored_bounds_ = bounds_;
     const gfx::Display display =
         gfx::Screen::GetScreenFor(NULL)->GetDisplayNearestWindow(window());
     bounds_ = display.bounds();
@@ skipping 1145 matching lines @@
   if (linux_ui) {
     ui::NativeTheme* native_theme = linux_ui->GetNativeTheme(window);
     if (native_theme)
       return native_theme;
   }
 
   return ui::NativeTheme::instance();
 }
 
 }  // namespace views