Right now we only do this in FrameLoaderClient::transitionToCommittedForNewPage, which is only called when we load uncached pages. If the page we are about to load is in the cache rameLoaderClient::transitionToCommittedFromCachedFrame is called instead, and we never set the adjustments. This results in the scrollbars for the main frame being mispositioned and nonfunctional in some cases.
Created attachment 48414 [details]
Attachment 48414 [details] did not pass style-queue:
Failed to run "WebKitTools/Scripts/check-webkit-style" exit_code: 1
WebKit/gtk/WebCoreSupport/FrameLoaderClientGtk.cpp:1131: Use 0 instead of NULL. [readability/null] 
WebKit/gtk/WebCoreSupport/FrameLoaderClientGtk.cpp:1142: Declaration has space between type name and * in Frame *frame [whitespace/declaration] 
Total errors found: 2
If any of these errors are false positives, please file a bug against check-webkit-style.
Comment on attachment 48414 [details]
r=me with the style issues reported by the bot fixed! =)
All done in r54559.