In an effort to speed up browser load times, Chrome has decided to block Adobe Flash ads by default. This change went into effect on September 1, 2015.
If you are currently running Flash display ads in your Google Adwords account, be sure to update those ads to HTML format as soon as possible to continue showing your ads on all browsers. Chrome accounts for a large percentage of the market share – currently over 60%. Not being present on Chrome could result in a huge decrease in your visibility.