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

chrome/browser/fullscreen_linux.cc

+// 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.
+
+#include "chrome/browser/fullscreen.h"
+
+#include <gdk/gdk.h>
+#include <gdk/gdkx.h>
+
+#include <algorithm>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "gfx/rect.h"
+#include "ui/base/x/x11_util.h"
+
+namespace {
+
+XID FindTopMostWindow(XID window) {
+  XID root, parent, *children;
+  unsigned int num_children;
+  if (!XQueryTree(ui::GetXDisplay(),
+                  window,
+                  &root,
+                  &parent,
+                  &children,
+                  &num_children))
+    return None;
+
+  // XQueryTree returns the children of |window| in bottom-to-top order. So
+  // we build the list from top to bottom.
+  std::vector<XID> windows;
+  for (int i = static_cast<int>(num_children - 1); i >= 0; --i)

[evanm, 2011/01/21 00:43:07]

One more minor comment:

static_cast<int>(num_children - 1)

if num_children is zero this will overflow.  Maybe that can't happen, but it'd
make me feel better if you did

static_cast<int>(num_children) - 1

[jianli, 2011/01/21 20:21:00]

Done.

+    windows.push_back(children[i]);
+
+  XFree(children);
+
+  for (std::vector<XID>::iterator iter = windows.begin();
+       iter != windows.end(); ++iter) {
+    XID window = *iter;
+
+    // Skip the invisible window.
+    if (!ui::IsWindowVisible(window))
+      continue;
+
+    // Check if the window is managed by the window manager.
+    if (ui::ExistsProperty(window, "WM_STATE"))
+      return window;
+
+    // Otherwise, try to check its child windows.
+    XID topmost_window = FindTopMostWindow(window);

[Daniel Erat, 2011/01/21 01:28:17]

This seems wrong.  It looks like it gets called recursively until you don't find
any child windows.  Ideally you'd just search with a depth of one -- in the
common case, the window manager is a reparenting one, so there will be one level
of windows between the root and the client windows.  In the less-common case,
the client windows will be direct children of the root.

Why not use gtk_util::EnumerateTopLevelWindows() from browser/ui/gtk/gtk_util.h,
which knows how to use _NET_CLIENT_LIST_STACKING if the WM supports it (most do)
to find the top client window without having to walk the tree?

[jianli, 2011/01/21 20:21:00]

Done.

+    if (topmost_window)
+      return topmost_window;
+  }
+
+  return None;
+}
+
+bool DoFullScreenCheck() {

[Daniel Erat, 2011/01/21 01:28:17]

Please give this function a more-descriptive name; "FullScreenCheck" doesn't
mean anything to me.  Something like "IsTopmostWindowFullscreen()" seems like it
might be more accurate.

[jianli, 2011/01/21 20:21:00]

Done.

+  // Find the topmost window.
+  XID topmost_window = FindTopMostWindow(ui::GetX11RootWindow());
+  if (topmost_window == None)
+    return false;
+
+  // Make sure it is not the desktop window.
+  Atom atom = gdk_x11_get_xatom_by_name_for_display(
+      gdk_display_get_default(), "_NET_WM_WINDOW_TYPE_DESKTOP");
+
+  std::vector<Atom> atom_properties;
+  if (ui::GetAtomArrayProperty(topmost_window,
+                                     "_NET_WM_WINDOW_TYPE",
+                                     &atom_properties) &&
+      std::find(atom_properties.begin(), atom_properties.end(), atom)
+          != atom_properties.end())
+    return false;
+
+  // If it is a GDK window, check it using gdk function.
+  GdkWindow* gwindow = gdk_window_lookup(topmost_window);

[Daniel Erat, 2011/01/21 01:28:17]

The docs for gdk_window_lookup() are vague: will it return a GdkWindow for every
X window, or only for X windows opened by GDK but possibly by other clients (I
don't know how it could check this unless GDK sets a property on every window it
opens), or only for X windows opened by this client?

[jianli, 2011/01/21 20:21:00]

I am not sure either. But I think it would be nice to check for this if we can
get a GDK window. Or I can remove this if X11 check is enough.

+  if (gwindow && topmost_window != GDK_ROOT_WINDOW())
+    return gdk_window_get_state(gwindow) == GDK_WINDOW_STATE_FULLSCREEN;
+
+  // Otherwise, do the check via xlib function.
+  return IsX11WindowFullScreen(topmost_window);
+}
+
+}
+
+bool IsX11WindowFullScreen(XID window) {

[Daniel Erat, 2011/01/21 01:28:17]

If you want to call this from other places (it looks like you do), it should
probably go in ui/base/x/x11_util.h instead.

[jianli, 2011/01/21 20:21:00]

Done.

+  // First check if _NET_WM_STATE property contains _NET_WM_STATE_FULLSCREEN.
+  Atom atom = gdk_x11_get_xatom_by_name_for_display(

[Daniel Erat, 2011/01/21 01:28:17]

It'd be good to cache this so you don't need to do a round trip to look it up
each time this is called.

[jianli, 2011/01/21 20:21:00]

Done.

+      gdk_display_get_default(), "_NET_WM_STATE_FULLSCREEN");
+
+  std::vector<Atom> atom_properties;
+  if (ui::GetAtomArrayProperty(window,
+                                     "_NET_WM_STATE",

[Daniel Erat, 2011/01/21 01:28:17]

fix indenting

[jianli, 2011/01/21 20:21:00]

Done.

+                                     &atom_properties) &&
+      std::find(atom_properties.begin(), atom_properties.end(), atom)
+          != atom_properties.end())
+    return true;
+
+  // As the last resort, check if the window size is as large as the main
+  // screen.
+  GdkRectangle monitor_rect;
+  gdk_screen_get_monitor_geometry(gdk_screen_get_default(), 0, &monitor_rect);
+
+  gfx::Rect window_rect;
+  if (!ui::GetWindowRect(window, &window_rect))
+    return false;
+
+  return monitor_rect.x == window_rect.x() &&
+         monitor_rect.y == window_rect.y() &&
+         monitor_rect.width == window_rect.width() &&
+         monitor_rect.height == window_rect.height();
+}
+
+bool IsFullScreenMode() {
+  gdk_error_trap_push();
+  bool is_fullscreen = DoFullScreenCheck();
+  bool got_error = gdk_error_trap_pop();
+  return is_fullscreen && !got_error;
+}