FrameView and navigation
Visiting a site can have certain changes on a FrameView that will not be undone when leaving it. The most prominent example is a fixed background (by CSS) which will disable using blit on scrolling. There might be different things as well. Another one would be the PageCache and navigation to pages in it. The result is that for every page navigation you will create a new FrameView. For most/all ports this is done in FrameLoaderClient::transitionToCommittedForNewPage(). There is even a…