[epiphany/mcatanzaro/cancellables: 2/3] web-process-extension: add cancellable and use it where required

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 36519e02de205750cd717eb55571643f9dd4563d
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Mon Dec 16 18:18:12 2019 -0600

    web-process-extension: add cancellable and use it where required
    
    It's not safe to make async function calls that could theoretically
    finish after the caller is destroyed. Now, in theory this should never
    happen, because the EphyWebProcessExtension is destroyed in an exit
    handler. But let's be robust and follow safe practices anyway.

 .../ephy-web-process-extension.c                     | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)
---
diff --git a/embed/web-process-extension/ephy-web-process-extension.c 
b/embed/web-process-extension/ephy-web-process-extension.c
index 4db9c7114..9fafbd4bb 100644
--- a/embed/web-process-extension/ephy-web-process-extension.c
+++ b/embed/web-process-extension/ephy-web-process-extension.c
@@ -45,6 +45,8 @@ struct _EphyWebProcessExtension {
   WebKitWebExtension *extension;
   gboolean initialized;
 
+  GCancellable *cancellable;
+
   EphyWebOverviewModel *overview_model;
   EphyPermissionsManager *permissions_manager;
 
@@ -377,6 +379,11 @@ ephy_web_process_extension_dispose (GObject *object)
 {
   EphyWebProcessExtension *extension = EPHY_WEB_PROCESS_EXTENSION (object);
 
+  if (extension->cancellable) {
+    g_cancellable_cancel (extension->cancellable);
+    g_clear_object (&extension->cancellable);
+  }
+
   g_clear_object (&extension->overview_model);
   g_clear_object (&extension->permissions_manager);
 
@@ -402,6 +409,7 @@ ephy_web_process_extension_class_init (EphyWebProcessExtensionClass *klass)
 static void
 ephy_web_process_extension_init (EphyWebProcessExtension *extension)
 {
+  extension->cancellable = g_cancellable_new ();
   extension->overview_model = ephy_web_overview_model_new ();
 }
 
@@ -463,7 +471,8 @@ web_view_query_usernames_ready_cb (WebKitWebPage            *web_page,
 
   reply = webkit_web_page_send_message_to_view_finish (web_page, result, &error);
   if (error) {
-    g_warning ("Error getting usernames from WebView: %s\n", error->message);
+    if (!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
+      g_warning ("Error getting usernames from WebView: %s\n", error->message);
     g_free (data);
     return;
   }
@@ -513,7 +522,8 @@ js_query_usernames (const char              *origin,
   data->frame_id = frame_id;
   message = webkit_user_message_new ("PasswordManager.QueryUsernames",
                                      g_variant_new ("s", origin));
-  webkit_web_page_send_message_to_view (web_page, message, NULL,
+  webkit_web_page_send_message_to_view (web_page, message,
+                                        extension->cancellable,
                                         (GAsyncReadyCallback)web_view_query_usernames_ready_cb,
                                         data);
 }
@@ -532,7 +542,8 @@ web_view_query_password_ready_cb (WebKitWebPage            *web_page,
 
   reply = webkit_web_page_send_message_to_view_finish (web_page, result, &error);
   if (error) {
-    g_warning ("Error getting password from WebView: %s\n", error->message);
+    if (!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
+      g_warning ("Error getting password from WebView: %s\n", error->message);
     g_free (data);
     return;
   }
@@ -586,7 +597,8 @@ js_query_password (const char              *origin,
   data->frame_id = frame_id;
   message = webkit_user_message_new ("PasswordManager.QueryPassword",
                                      g_variant_new ("(ssmsmss)", origin, target_origin, username, 
username_field, password_field));
-  webkit_web_page_send_message_to_view (web_page, message, NULL,
+  webkit_web_page_send_message_to_view (web_page, message,
+                                        extension->cancellable,
                                         (GAsyncReadyCallback)web_view_query_password_ready_cb,
                                         data);
 }