linux_aura: Double clicking the titlebar should toggle maximized.

ui/views/widget/desktop_aura/desktop_root_window_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_root_window_host_x11.h"
 
 #include <X11/extensions/shape.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/Xatom.h>
 #include <X11/Xregion.h>
@@ skipping 244 matching lines @@
   // window. Otherwise activation gets screwy.
   gfx::NativeView parent = params.parent;
   if (!params.child && params.parent)
     parent->AddTransientChild(content_window_);
 
   // Ensure that the X11DesktopHandler exists so that it dispatches activation
   // messages to us.
   X11DesktopHandler::get();
 
   // TODO(erg): Unify this code once the other consumer goes away.
-  x11_window_event_filter_.reset(new X11WindowEventFilter(root_window_));
+  x11_window_event_filter_.reset(new X11WindowEventFilter(root_window_, this));
   x11_window_event_filter_->SetUseHostWindowBorders(false);
   desktop_native_widget_aura_->root_window_event_filter()->AddHandler(
       x11_window_event_filter_.get());
 
   x11_window_move_client_.reset(new X11DesktopWindowMoveClient);
   aura::client::SetWindowMoveClient(root_window_->window(),
                                     x11_window_move_client_.get());
 
   native_widget_delegate_->OnNativeWidgetCreated(true);
 }
@@ skipping 1254 matching lines @@
   if (linux_ui) {
     ui::NativeTheme* native_theme = linux_ui->GetNativeTheme();
     if (native_theme)
       return native_theme;
   }
 
   return ui::NativeTheme::instance();
 }
 
 }  // namespace views