Pulls ActiveWindowWatcher into app so that we can use it in

views. Converts from using notification server to observer as
notification service is chrome only.
Also changes the pointer type used by window_gtk to be a left arrow.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/245016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@27398 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 113 insertions, 0 deletions

diff --git a/app/active_window_watcher_x.cc b/app/active_window_watcher_x.cc
new file mode 100644
index 0000000..d834a5c
--- /dev/null
+++ b/app/active_window_watcher_x.cc
@@ -0,0 +1,63 @@
+// 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 <X11/Xlib.h>
+#include <gdk/gdk.h>
+#include <gdk/gdkx.h>
+
+#include "app/active_window_watcher_x.h"
+
+// static
+void ActiveWindowWatcherX::AddObserver(Observer* observer) {
+  Singleton<ActiveWindowWatcherX>::get()->observers_.AddObserver(observer);
+}
+
+// static
+void ActiveWindowWatcherX::RemoveObserver(Observer* observer) {
+  Singleton<ActiveWindowWatcherX>::get()->observers_.RemoveObserver(observer);
+}
+
+ActiveWindowWatcherX::ActiveWindowWatcherX() {
+  Init();
+}
+
+void ActiveWindowWatcherX::Init() {
+  // Set up X Event filter to listen for PropertyChange X events.  These events
+  // tell us when the active window changes.
+  GdkWindow* root = gdk_screen_get_root_window(gdk_screen_get_default());
+  gdk_window_add_filter(root, &ActiveWindowWatcherX::OnWindowXEvent, this);
+  XSelectInput(GDK_WINDOW_XDISPLAY(root), GDK_WINDOW_XID(root),
+               PropertyChangeMask);
+}
+
+void ActiveWindowWatcherX::NotifyActiveWindowChanged() {
+  GdkWindow* active_window = gdk_screen_get_active_window(
+      gdk_screen_get_default());
+
+  // If the window manager doesn't support _NET_ACTIVE_WINDOW, we don't know
+  // which window is active and just give up.
+  if (!active_window)
+    return;
+
+  FOR_EACH_OBSERVER(Observer, observers_, ActiveWindowChanged(active_window));
+}
+
+GdkFilterReturn ActiveWindowWatcherX::OnWindowXEvent(GdkXEvent* xevent,
+    GdkEvent* event, gpointer window_watcher) {
+  static const GdkAtom kNetActiveWindow = gdk_atom_intern(
+      "_NET_ACTIVE_WINDOW", FALSE);
+  static const Atom kNetActiveWindowAtom = gdk_x11_atom_to_xatom_for_display(
+        gdk_screen_get_display(gdk_screen_get_default()), kNetActiveWindow);
+
+  ActiveWindowWatcherX* watcher = reinterpret_cast<ActiveWindowWatcherX*>(
+      window_watcher);
+  XEvent* xev = static_cast<XEvent*>(xevent);
+
+  if (xev->xany.type == PropertyNotify &&
+      xev->xproperty.atom == kNetActiveWindowAtom) {
+    watcher->NotifyActiveWindowChanged();
+  }
+
+  return GDK_FILTER_CONTINUE;
+}
diff --git a/app/active_window_watcher_x.h b/app/active_window_watcher_x.h
new file mode 100644
index 0000000..2ea524e
--- /dev/null
+++ b/app/active_window_watcher_x.h
@@ -0,0 +1,48 @@
+// 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.
+
+#ifndef APP_ACTIVE_WINDOW_WATCHER_X_H_
+#define APP_ACTIVE_WINDOW_WATCHER_X_H_
+
+#include <gdk/gdk.h>
+
+#include "base/basictypes.h"
+#include "base/observer_list.h"
+#include "base/singleton.h"
+
+// This is a helper class that is used to keep track of which window the X
+// window manager thinks is active. Add an Observer to listener for changes to
+// the active window.
+class ActiveWindowWatcherX {
+ public:
+  class Observer {
+   public:
+    virtual void ActiveWindowChanged(GdkWindow* active_window) = 0;
+  };
+
+  static void AddObserver(Observer* observer);
+  static void RemoveObserver(Observer* observer);
+
+ private:
+  friend struct DefaultSingletonTraits<ActiveWindowWatcherX>;
+
+  ActiveWindowWatcherX();
+
+  void Init();
+
+  // Sends a notification out through the NotificationService that the active
+  // window has changed.
+  void NotifyActiveWindowChanged();
+
+  // Callback for PropertyChange XEvents.
+  static GdkFilterReturn OnWindowXEvent(GdkXEvent* xevent,
+                                        GdkEvent* event,
+                                        gpointer window_watcher);
+
+  ObserverList<Observer> observers_;
+
+  DISALLOW_COPY_AND_ASSIGN(ActiveWindowWatcherX);
+};
+
+#endif  // APP_ACTIVE_WINDOW_WATCHER_X_H_
diff --git a/app/app.gyp b/app/app.gyp
index 7c61d17..73d65ba 100644
--- a/app/app.gyp
+++ b/app/app.gyp
@@ -59,6 +59,8 @@
         # All .cc, .h, and .mm files under app/ except for tests.
         'animation.cc',
         'animation.h',
+        'active_window_watcher_x.cc',
+        'active_window_watcher_x.h',
         'app_paths.h',
         'app_paths.cc',
         'app_switches.h',