What does riot define as a "decided game"?

One of the balance goals is to reduce the number of "decided games" by giving teams the ability to come back from gold deficits, and if a game becomes decided, it ends quickly. So, what is the gold deficit limit to determine if a game is decided? Is it even based on gold. Aside from killing the nexus, here are some common win conditions: Triple inhib Double inhib + baron Triple infernal Baron + second elder (with at least 2 elemental buffs, or at least 1 infernal) Fed vayne / twitch with protection support