It was previously announced that Chrome would begin pausing Flash ads by default in an effort to improve overall performance for users, and that change is about to begin. These changes will begin to roll out starting September 1, meaning that the ads will no longer auto-play on pages.
Most of the Flash ads that are uploaded to AdWords are automatically converted to HTML5, but advertisers will need to make a few changes to ensure their ads can be automatically converted going forward. If you are an advertiser, be sure to check out the changes at the link below.
The change is rolling out beginning September 1, meaning that it won't be everywhere on that date. This is definitely a great step forward for users.