Google's NSFW filter option SafeSearch has been updated to automatically hide explicit content from showing up in search results, which means you'll just have to be a lot more specific about what you're looking for when it comes to adult-only content. Read Google's official statement via CNET:
"We are not censoring any adult content, and want to show users exactly what they are looking for — but we aim not to show sexually-explicit results unless a user is specifically searching for them. We use algorithms to select the most relevant results for a given query. If you're looking for adult content, you can find it without having to change the default setting — you just may need to be more explicit in your query if your search terms are potentially ambiguous."