[epiphany] Fix UI process crash if the web process crashes on start

[Michael Catanzaro <mcatanzaro src gnome org>]

commit ff027c61b48d354beceebfe2b6a37c27fb2ad139
Author: Michael Catanzaro <mcatanzaro igalia com>
Date:   Sat Feb 21 10:19:24 2015 -0600

    Fix UI process crash if the web process crashes on start
    
    Currently there is a WebKit bug that causes the web process to crash
    when we use webkit_web_view_load_alternate_html() on a local page, say
    because Epiphany was closed when a file:// URI was opened in an embed
    other than the focused embed. That crash occurs after
    web_extension_appeared_cb() but prior to
    web_extension_proxy_created_cb(), triggering a call to
    web_extension_vanished_cb(), which deletes the EphyWebExtensionProxy
    object that is expected to still be alive when
    web_extension_proxy_created_cb() is called, crashing the UI process.
    We can fix this with a ref/unref pair.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=744896

 embed/ephy-web-extension-proxy.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/embed/ephy-web-extension-proxy.c b/embed/ephy-web-extension-proxy.c
index 773e0f9..2e03996 100644
--- a/embed/ephy-web-extension-proxy.c
+++ b/embed/ephy-web-extension-proxy.c
@@ -90,6 +90,8 @@ web_extension_proxy_created_cb (GDBusProxy *proxy,
     g_warning ("Error creating web extension proxy: %s\n", error->message);
     g_error_free (error);
   }
+
+  g_object_unref (web_extension);
 }
 
 static void
@@ -110,7 +112,9 @@ web_extension_appeared_cb (GDBusConnection *connection,
                     EPHY_WEB_EXTENSION_INTERFACE,
                     web_extension->priv->cancellable,
                     (GAsyncReadyCallback)web_extension_proxy_created_cb,
-                    web_extension);
+                    /* Ref here because the web process could crash, triggering
+                     * web_extension_vanished_cb() before this finishes. */
+                    g_object_ref (web_extension));
 }
 
 static void