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You may recall that yesterday I was just reading through the code, writing up my understanding of how the flow differs between ESR 78 and ESR 91 during the initialisation steps of the offscreen rendering pipeline.

By the end of that discussion I'd come up with a set of tasks to perform:
 
I've not done these quite in the order I said I would. This evening I've completed the second of the tasks, removing the extra call to GetAppDisplay() from the ESR 91 code. I've done this by adding an aDisplay parameter to DefaultEglLibrary() so it now looks like this:

RefPtr<GLLibraryEGL> DefaultEglLibrary(nsACString* const out_failureId, 
    EGLDisplay aDisplay) {
  StaticMutexAutoLock lock(sMutex);
  if (!gDefaultEglLibrary) {
    gDefaultEglLibrary = GLLibraryEGL::Create(out_failureId, aDisplay);
    if (!gDefaultEglLibrary) {
      NS_WARNING(&quot;GLLibraryEGL::Create failed&quot;);
    }
  }
  return gDefaultEglLibrary.get();
}

As a consequence I'm able to remove the call to GetAppDisplay() that was happening inside of this method. This has actually ended up simplifying the code as well. There's still a call to GetAppDisplay() inside GLContextEGLFactory::CreateImpl() which I'd like to get rid of, but there's no really obvious way to do this right now.

That still leaves the task of comparing the EGL library creation code. I realise that I also left another task outstanding from a few days back, which is to place breakpoints on the ESR 91 code everywhere the display is used and check the value is the same all the way through. I did this for ESR 78 on Day 207 and — while it was rather dull and laborious — it did help me to understand the execution flow. It also highlighted that all the display values are the same (set to 0x01) throughout the execution. I'd be wanting to see something similar on ESR 91.

That's all going to be for tomorrow though. Overnight I plan to build the packages so I can test out the GetAppDisplay() changes I made today.

If you'd like to read any of my other gecko diary entries, they're all available on my Gecko-dev Diary page.