[Firefox] Lazy load network.js in PdfStreamConverter.js

[Snuffleupagus]

Inspired by this thread, started by @nnethercote on dev.platform: https://groups.google.com/forum/#!topic/mozilla.dev.platform/sAuhWQOAWic.

This PR changes network.js to be lazily loaded instead, to delay loading it until it's needed and to avoid affecting the browser start-up.

I my testing this works fine, and given that we already lazy load other modules (e.g. PdfJsTelemetry.jsm) I don't think that there should be any issues with this change.

[nnethercote]

Nice!

[nnethercote]

While we're here: the other pdf.js compartments seen at start-up:

[System Principal], resource://pdf.js/default_preferences.js
[System Principal], resource://pdf.js/PdfJs.jsm
[System Principal], resource://pdf.js/PdfRedirector.jsm
[System Principal], resource://pdf.js/PdfStreamConverter.jsm

Are they all necessary? If so, could any be combined easily? default_preferences.js is tiny...

[Snuffleupagus]

Are they all necessary?

The way that the code is currently structured, I think most of them are.
PdfJs.jsm is used to register PDF.js as the handler for PDF files, and is invoked by: http://dxr.mozilla.org/mozilla-central/source/browser/components/nsBrowserGlue.js?from=nsBrowserGlue.js (lines #56-57 and #476).

Both PdfStreamConverter.jsm and PdfRedirector.jsm are then (indirectly) loaded by https://github.com/mozilla/pdf.js/blob/master/extensions/firefox/content/PdfJs.jsm#L111 (https://github.com/mozilla/pdf.js/blob/master/extensions/firefox/content/PdfJs.jsm#L244).

If so, could any be combined easily?

I don't know enough about these parts of the code base to answer that, sorry!

default_preferences.js is tiny...

Yes, and I have a patch ready that use the preprocessor to include this code where necessary. However, I wanted to submit this PR first to gauge the interest in these kind of changes before submitting that one.

[Snuffleupagus]

Actually, it seems probable (I haven't tested though) that we could change these to be lazily loaded as well: https://github.com/mozilla/pdf.js/blob/master/extensions/firefox/content/PdfJs.jsm#L37-L38.
But I'm not sure if it would really make a difference, given that they are both needed in PdfJs.init.

Edit: It might actually be worthwhile to change this anyway, since they are currently loaded irrespective of whether PDF.js is active or not.

[yurydelendik]

/botio-linux preview

[pdfjsbot]

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Live output at: http://107.21.233.14:8877/b59b9f658a5a0c4/output.txt

[pdfjsbot]

From: Bot.io (Linux)

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Full output at http://107.21.233.14:8877/b59b9f658a5a0c4/output.txt

Total script time: 0.40 mins

Published

• Viewer: http://107.21.233.14:8877/b59b9f658a5a0c4/web/viewer.html
• B2G Viewer: http://107.21.233.14:8877/b59b9f658a5a0c4/extensions/b2g/content/web/viewer.html
• Extension: http://107.21.233.14:8877/b59b9f658a5a0c4/extensions/firefox/pdf.js.xpi
• Extension (AMO): http://107.21.233.14:8877/b59b9f658a5a0c4/extensions/firefox/pdf.js.amo.xpi

[yurydelendik]

Thanks