Add some logging to indicate what layout milestones have been reached. This should help us determine if there's a client, rendering, layout, or some other issue when page content does not appear in the client window. <rdar://problem/49128952>
The logging is being added to WebFrameLoaderClient::dispatchDidReachLayoutMilestone. This seems like a nice central place to capture layout milestones. However, it will only log notifications that are being sent to clients. It does not indicate all milestones that have occurred. That is, it does not report milestones that are filtered out due to client disinterest. There doesn't seem to be a good central place to capture all milestones, regardless of client interest.
$ rg 'dispatchDidReachLayoutMilestone' low.txt 2019-03-22 14:19:50.805015-0700 0x64f1e3 Default 0x0 1649 0 com.apple.WebKit.WebContent.Development: (WebKit) [com.apple.WebKit:Layout] 0x651bf7ae0 - WebFrameLoaderClient::dispatchDidReachLayoutMilestone: dispatching DidFirstLayoutForFrame, page = 0x7fcffe004e08 2019-03-22 14:19:50.805017-0700 0x64f1e3 Default 0x0 1649 0 com.apple.WebKit.WebContent.Development: (WebKit) [com.apple.WebKit:Layout] 0x651bf7ae0 - WebFrameLoaderClient::dispatchDidReachLayoutMilestone: dispatching didCompletePageTransition, page = 0x7fcffe004e08 2019-03-22 14:19:50.805029-0700 0x64f1e3 Default 0x0 1649 0 com.apple.WebKit.WebContent.Development: (WebKit) [com.apple.WebKit:Layout] 0x651bf7ae0 - WebFrameLoaderClient::dispatchDidReachLayoutMilestone: dispatching DidReachLayoutMilestone, page = 0x7fcffe004e08, milestones = DidFirstLayout, DidFirstVisuallyNonEmptyLayout 2019-03-22 14:19:50.805031-0700 0x64f1e3 Default 0x0 1649 0 com.apple.WebKit.WebContent.Development: (WebKit) [com.apple.WebKit:Layout] 0x651bf7ae0 - WebFrameLoaderClient::dispatchDidReachLayoutMilestone: dispatching DidFirstVisuallyNonEmptyLayoutForFrame, page = 0x7fcffe004e08 2019-03-22 14:19:50.860795-0700 0x64f1e3 Default 0x0 1649 0 com.apple.WebKit.WebContent.Development: (WebKit) [com.apple.WebKit:Layout] 0x651bf7ae0 - WebFrameLoaderClient::dispatchDidReachLayoutMilestone: dispatching DidReachLayoutMilestone, page = 0x7fcffe004e08, milestones = DidFirstMeaningfulPaint
<rdar://problem/49128952>
Created attachment 365762 [details] Patch
Comment on attachment 365762 [details] Patch Clearing flags on attachment: 365762 Committed r243453: <https://trac.webkit.org/changeset/243453>
All reviewed patches have been landed. Closing bug.