First cut at Exit Fullscreen bubble on Linux.

chrome/browser/gtk/browser_window_gtk.cc

 // Copyright (c) 2009 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 "chrome/browser/gtk/browser_window_gtk.h"
 
 #include <gdk/gdkkeysyms.h>
 #include <X11/XF86keysym.h>
 
 #include <string>
@@ skipping 28 matching lines @@
 #include "chrome/browser/gtk/bookmark_bar_gtk.h"
 #include "chrome/browser/gtk/bookmark_manager_gtk.h"
 #include "chrome/browser/gtk/browser_titlebar.h"
 #include "chrome/browser/gtk/browser_toolbar_gtk.h"
 #include "chrome/browser/gtk/cairo_cached_surface.h"
 #include "chrome/browser/gtk/clear_browsing_data_dialog_gtk.h"
 #include "chrome/browser/gtk/download_in_progress_dialog_gtk.h"
 #include "chrome/browser/gtk/download_shelf_gtk.h"
 #include "chrome/browser/gtk/edit_search_engine_dialog.h"
 #include "chrome/browser/gtk/find_bar_gtk.h"
+#include "chrome/browser/gtk/fullscreen_exit_bubble_gtk.h"
 #include "chrome/browser/gtk/gtk_floating_container.h"
 #include "chrome/browser/gtk/go_button_gtk.h"
 #include "chrome/browser/gtk/gtk_theme_provider.h"
 #include "chrome/browser/gtk/import_dialog_gtk.h"
 #include "chrome/browser/gtk/info_bubble_gtk.h"
 #include "chrome/browser/gtk/infobar_container_gtk.h"
 #include "chrome/browser/gtk/keyword_editor_view.h"
 #include "chrome/browser/gtk/nine_box.h"
 #include "chrome/browser/gtk/repost_form_warning_gtk.h"
 #include "chrome/browser/gtk/status_bubble_gtk.h"
@@ skipping 1359 matching lines @@
 
   if (changed_mask & GDK_WINDOW_STATE_FULLSCREEN) {
     bool is_fullscreen = state & GDK_WINDOW_STATE_FULLSCREEN;
     browser_->UpdateCommandsForFullscreenMode(is_fullscreen);
     if (is_fullscreen) {
       UpdateCustomFrame();
       toolbar_->Hide();
       tabstrip_->Hide();
       if (IsBookmarkBarSupported())
         bookmark_bar_->EnterFullscreen();
+      fullscreen_exit_bubble_.reset(new FullscreenExitBubbleGtk(
+          GTK_FLOATING_CONTAINER(render_area_floating_container_)));
       gtk_widget_hide(toolbar_border_);
 #if defined(OS_CHROMEOS)
       if (main_menu_button_)
         gtk_widget_hide(main_menu_button_->widget());
       if (compact_navbar_hbox_)
         gtk_widget_hide(compact_navbar_hbox_);
       if (status_area_)
         status_area_->GetWidget()->Hide();
 #endif
     } else {
+      fullscreen_exit_bubble_.reset();
       UpdateCustomFrame();
       ShowSupportedWindowFeatures();
 
       gtk_widget_show(toolbar_border_);
       gdk_window_lower(toolbar_border_->window);
     }
   }
 
   UpdateWindowShape(bounds_.width(), bounds_.height());
   SaveWindowPosition();
@@ skipping 883 matching lines @@
   // are taken from the WMs' source code.
   return (wm_name == "Blackbox" ||
           wm_name == "compiz" ||
           wm_name == "e16" ||  // Enlightenment DR16
           wm_name == "KWin" ||
           wm_name == "Metacity" ||
           wm_name == "Mutter" ||
           wm_name == "Openbox" ||
           wm_name == "Xfwm4");
 }