Add additional tracking information to mediawiki.searchSuggest

Adds a few pieces of information to improve tracking of autocomplete
usage.

* When using Special:Search 'go' feature forward wprov parameter to redirect
* Include a data attribute indicating autocomplete location to
  differentiate usage of the header and Special:Search content autocompletes
* Report exact query string that was used for impression-results
* Add handling to allow searchSuggest subscribers to append tracking
  information to generated article links
* Add a new hook, SpecialSearchGoResult, that can either change the url
  redirected to in the 'go' feature or cancel it entirely.

Bug: T125915
Change-Id: Iec7171fcf301f1659d852afa87ce271f468177c1

1 files changed, 4 insertions, 3 deletions

diff --git a/resources/src/jquery/jquery.suggestions.js b/resources/src/jquery/jquery.suggestions.js
index 01d9a43d61e4..1f977bf910e0 100644
--- a/resources/src/jquery/jquery.suggestions.js
+++ b/resources/src/jquery/jquery.suggestions.js
@@ -181,7 +181,7 @@
 						if ( +new Date() - cache[ val ].timestamp < context.config.cacheMaxAge ) {
 							context.data.$textbox.suggestions( 'suggestions', cache[ val ].suggestions );
 							if ( typeof context.config.update.after === 'function' ) {
-								context.config.update.after.call( context.data.$textbox );
+								context.config.update.after.call( context.data.$textbox, cache[ val ].metadata );
 							}
 							cacheHit = true;
 						} else {
@@ -193,15 +193,16 @@
 						context.config.fetch.call(
 							context.data.$textbox,
 							val,
-							function ( suggestions ) {
+							function ( suggestions, metadata ) {
 								suggestions = suggestions.slice( 0, context.config.maxRows );
 								context.data.$textbox.suggestions( 'suggestions', suggestions );
 								if ( typeof context.config.update.after === 'function' ) {
-									context.config.update.after.call( context.data.$textbox );
+									context.config.update.after.call( context.data.$textbox, metadata );
 								}
 								if ( context.config.cache ) {
 									cache[ val ] = {
 										suggestions: suggestions,
+										metadata: metadata,
 										timestamp: +new Date()
 									};
 								}