Bugzilla

The current code waits for an error event if an image could not be loaded to
convert them to data: URLs. These error events are fired after the load event
and there is not mechanism besides waiting to be sure all images have been
converted.

The background image is already converted manually. This patch moves the conversion
process of the other images out of the error event and handles them alongside the
background image. We still get CSP errors for the original imap:// urls, but we are
now able to set a well defined status, once the content of the editor is fully loaded.

This patch also moves all other WebExtension APIs which act on the compose window to
use the new compose-editor-content-ready event.

The current code waits for an error event if an image could not be loaded to
convert them to data: URLs. These error events are fired after the load event
and there is no mechanism besides waiting to be sure all images have been
converted.

The background image is already converted manually. This patch moves the conversion
process of the other images out of the error event and handles them alongside the
background image. We still get CSP errors for the original imap:// URLSs, but we are
now able to set a well defined status, once the content of the editor is fully loaded.

This patch also moves all WebExtension APIs which act on the compose window to
use the new compose-editor-content-ready event.

The WebExtension API currently waits for the `compose-editor-ready` event to detect
when a compose window is ready. However, certain modifications are still applied
after that event, most notably image conversions from mailnews URLs to `data:`
URLs.

Due to other code changes, the event is now seen too early by WebExtensions. This
patch aims to correctly wait until after the image conversion has finished.

The current code waits for an error event if an image could not be loaded, in order
to convert it to a `data:` URL. These error events are fired after the load event,
and there is no mechanism besides "waiting a bit" to ensure all images have been
converted.

The background image is already converted manually. This patch moves the conversion
process of the other images out of the error event and handles them alongside the
background image. We still get CSP errors for the original `imap://` URLs, but we
are now able to set a well-defined status once the content of the editor is fully
loaded.

This patch also moves all WebExtension APIs that act on the compose window to use
the new `compose-editor-content-ready` event.