What is Safari Safe Browsing Data and why does it need to copy every time I sync my iDevice?
Google Safe Browsing Data Syncs to iOS Devices Via iTunes explains what it is:


  This database, provided by Google, is used by mobile Safari to check for known malicious web sites. To check if this is activated on your iOS device, go to Settings > Safari, then look for the Fraud Warning slider. If it’s not set to “On,” do so; it’s a good way to protect your device and yourself from known malicious websites.