Do not show notifications when in fullscreen or screensaver mode....

chrome/browser/fullscreen.h

+// Copyright (c) 2011 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.
+
+#ifndef CHROME_BROWSER_FULLSCREEN_H_
+#define CHROME_BROWSER_FULLSCREEN_H_
+#pragma once
+
+#include "build/build_config.h"
+
+#if defined(OS_LINUX)
+#include "ui/base/x/x11_util.h" // For definition of XID.
+#endif
+
+// For MacOSX, InitFullScreenMonitor needs to be called first to setup the
+// monitor. StopFullScreenMonitor should be called if it is not needed any more.
+#if defined(OS_MACOSX)
+void InitFullScreenMonitor();
+void StopFullScreenMonitor();
+#endif
+
+// This helper function is needed by screensaver detection on Linux.
+#if defined(OS_LINUX)
+bool IsX11WindowFullScreen(XID window);
+#endif
+
+bool IsFullScreenMode();
+
+#endif  // CHROME_BROWSER_FULLSCREEN_H_