Test page for bug 1108017

To get started:

• Set privacy.trackingprotection.lower_network_priority to true in about:config.
• Run export MOZ_LOG=nsChannelClassifier:3 before starting Firefox in a terminal.

Then ensure that in the debug log, you see something like:

nsChannelClassifier[0x7fa4efb75100]: Enabling tracking protection checks on channel[0x7fa4f2f4a050] with uri https://itisatracker.org/green-tick.png for toplevel window uri https://itisatracker.org/
nsChannelClassifier[0x7fa4efb75100]: Checking blacklist for uri=https://itisatracker.org/green-tick.png
TrackingURICallback[0x7fa4efb75100]:OnClassifyComplete shouldEnableTrackingProtection=0, shouldEnableTrackingAnnnotation=1
TrackingURICallback[0x7fa4efb75100]::OnBlacklistResult channel[0x7fa4f2f4a050] uri=https://itisatracker.org/green-tick.png, is in blacklist. Start checking whitelist.
nsChannelClassifier[0x7fa4efb75100]: Looking for http://itisatracker.org/?resource=itisatracker.org in the whitelist (channel=0x7fa4f2f4a050)
TrackingURICallback[0x7fa4efb75100]:OnClassifyComplete shouldEnableTrackingProtection=0, shouldEnableTrackingAnnnotation=1
TrackingURICallback[0x7fa4efb75100]::OnWhitelistResult channel[0x7fa4f2f4a050] uri=https://itisatracker.org/green-tick.png, should not be whitelisted
TrackingURICallback[0x7fa4efb75100]::OnTrackerFound, annotating channel[0x7fa4f2f4a050]
nsChannelClassifier[0x7fa4efb75100]: Classifying principal https://itisatracker.org/green-tick.png on channel[0x7fa4f2f4a050]
nsChannelClassifier::MarkEntryClassified[NS_OK] https://itisatracker.org/green-tick.png
        

without a line like this:

Setting PRIORITY_LOWEST for channel[0x7f71d167e050] (https://itisatracker.org/green-tick.png)