[gnome-shell] browser-plugin: try to avoid a crash

[Michael Catanzaro <mcatanzaro src gnome org>]

commit faae1a028e1bd3e6f6f078f2ed523a41787a17d5
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Sun Sep 27 12:07:17 2015 -0500

    browser-plugin: try to avoid a crash
    
    Quite tempted to delete this unmaintained and unreliable plugin, but I
    can stand it not working so long as it at least stops crashing, so let's
    try this first.
    
    Hopefully mitigates bug #737932.

 browser-plugin/browser-plugin.c |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)
---
diff --git a/browser-plugin/browser-plugin.c b/browser-plugin/browser-plugin.c
index 59832ff..e8b5cf6 100644
--- a/browser-plugin/browser-plugin.c
+++ b/browser-plugin/browser-plugin.c
@@ -282,6 +282,14 @@ on_shell_signal (GDBusProxy *proxy,
 {
   PluginObject *obj = user_data;
 
+  /* FIXME: We have half a dozen bug reports in which this function crashes in
+   * WebKit due to a null NPObject. This should never happen, but since it is
+   * happening, let's turn the crash into a critical.
+   *
+   * https://bugzilla.gnome.org/show_bug.cgi?id=737932
+   */
+  g_return_if_fail (obj->instance);
+
   if (strcmp (signal_name, "ExtensionStatusChanged") == 0)
     {
       gchar *uuid;
@@ -312,6 +320,12 @@ on_shell_appeared (GDBusConnection *connection,
 {
   PluginObject *obj = (PluginObject*) user_data;
 
+  /* FIXME: Not sure if this is ever hit or not, but let's play it safe.
+   *
+   * https://bugzilla.gnome.org/show_bug.cgi?id=737932
+   */
+  g_return_if_fail (obj->instance);
+
   if (obj->restart_listener)
     {
       NPVariant result = { NPVariantType_Void };