Followup 2f2da72747
This commit moves topic view tracking from happening
every time a Topic is requested, which is susceptible
to inflating numbers of views from web crawlers, to
our request tracker middleware.
In this new location, topic views are only tracked when
the following headers are sent:
* HTTP_DISCOURSE_TRACK_VIEW - This is sent on every page navigation when
clicking around the ember app. We count these as browser page views
because we know it comes from the AJAX call in our app. The topic ID
is extracted from HTTP_DISCOURSE_TRACK_VIEW_TOPIC_ID
* HTTP_DISCOURSE_DEFERRED_TRACK_VIEW - Sent when MessageBus initializes
after first loading the page to count the initial page load view. The
topic ID is extracted from HTTP_DISCOURSE_DEFERRED_TRACK_VIEW.
This will bring topic views more in line with the change we
made to page views in the referenced commit and result in
more realistic topic view counts.
Our 'page_view_crawler' / 'page_view_anon' metrics are based purely on the User Agent sent by clients. This means that 'badly behaved' bots which are imitating real user agents are counted towards 'anon' page views.
This commit introduces a new method of tracking visitors. When an initial HTML request is made, we assume it is a 'non-browser' request (i.e. a bot). Then, once the JS application has booted, we notify the server to count it as a 'browser' request. This reliance on a JavaScript-capable browser matches up more closely to dedicated analytics systems like Google Analytics.
Existing data collection and graphs are unchanged. Data collected via the new technique is available in a new 'experimental' report.
