GTK: Provide GTK+ themed notifications.

chrome/browser/gtk/notifications/balloon_view_gtk.h

Index: chrome/browser/gtk/notifications/balloon_view_gtk.h
diff --git a/chrome/browser/gtk/notifications/balloon_view_gtk.h b/chrome/browser/gtk/notifications/balloon_view_gtk.h
index 9412cadf11fb8b0a3a61acda18401276681e8c16..de628b4c65465454dbb948ce5ebf0a1d37c895ec 100644
--- a/chrome/browser/gtk/notifications/balloon_view_gtk.h
+++ b/chrome/browser/gtk/notifications/balloon_view_gtk.h
@@ -21,6 +21,7 @@
 
 class BalloonCollection;
 class BalloonViewHost;
+class GtkThemeProvider;
 class MenuGtk;
 class NineBox;
 class NotificationDetails;
@@ -101,6 +102,8 @@ class BalloonViewImpl : public BalloonView,
   // Non-owned pointer to the balloon which owns this object.
   Balloon* balloon_;
 
+  GtkThemeProvider* theme_provider_;
+
   // The window that contains the frame of the notification.
   GtkWidget* frame_container_;