commit 3efe8736a302182bff2e9101044fd8e15668bbb6
author bokan <bokan@chromium.org> Wed Jul 06 23:27:44 2016
committer Commit bot <commit-bot@chromium.org> Wed Jul 06 23:30:32 2016
tree 0999c9cfec26e18c841930707cc828e7b9ad9bb3
parent acc2fb2eaf19f06817b8ef90b64b195d032a662a

Moved RootFrameViewport creation to happen after document attachment

I previously placed this to happen just before the first layout but that was
overly conservative; we really just need the document to be attached. This will
allow constructing a ViewportScrollCallback for a FrameView in just one place
for both root and nested frames. This will be needed in the setRootScroller
proposal in future patches.

BUG=505516

Review-Url: https://codereview.chromium.org/2123663003
Cr-Commit-Position: refs/heads/master@{#403973}