Edit: The linked article is now updated, at the time it was basically just a paragraph stating the fine.
That doc says Google's deals with publishers relating to AdSense for Search (which e.g. shows ads in newspaper sites' on-site search results) harmed competition by restricting what their partners could do with other potential providers. And that this was abuse of Google's dominant position in the relevant market.
> Google's provision of online search advertising intermediation services to the most commercially important publishers took place via agreements that were individually negotiated. The Commission has reviewed hundreds of such agreements in the course of its investigation and found that:
> Starting in 2006, Google included exclusivity clauses in its contracts. This meant that publishers were prohibited from placing any search adverts from competitors on their search results pages. The decision concerns publishers whose agreements with Google required such exclusivity for all their websites.
> As of March 2009, Google gradually began replacing the exclusivity clauses with so-called “Premium Placement” clauses. These required publishers to reserve the most profitable space on their search results pages for Google's adverts and request a minimum number of Google adverts. As a result, Google's competitorswere prevented from placing their search adverts in the most visible and clicked on parts of the websites' search results pages.
> As of March 2009, Google also included clauses requiring publishers to seek written approval from Google before making changes to the way in which any rival adverts were displayed. This meant that Google could control how attractive, and therefore clicked on, competing search adverts could be.
> Therefore, Google first imposed an exclusive supply obligation, which prevented competitors from placing any search adverts on the commercially most significant websites. Then, Google introduced what it called its “relaxed exclusivity” strategy aimed at reserving for its own search adverts the most valuable positions and at controlling competing adverts' performance.
> Google's practices covered over half the market by turnover throughout most of the period. Google's rivals were not able to compete on the merits, either because there was an outright prohibition for them to appear on publisher websites or because Google reserved for itself by far the most valuable commercial space on those websites, while at the same time controlling how rival search adverts could appear.
""""In 2006, Google started to include "exclusivity clauses" in contracts which stopped publishers from placing ads from Google rivals such as Microsoft and Yahoo on search pages, the Commission said."""
> In July 2018, the Commission fined Google €4.34 billion for illegal practices regarding Android mobile devices to strengthen the dominance of Google's search engine.