commit 1d95c6320dce15e12545ac8856ab9f0e77aa12ed
author csharrison <csharrison@chromium.org> Fri Feb 26 16:41:43 2016
committer Commit bot <commit-bot@chromium.org> Fri Feb 26 16:43:11 2016
tree 7e4bb31900d062e98dc27189f450288614a3b31d
parent 3fa2f06f7b1026322b9ed225002833d217acc5fc

Protect the provisional loader from detaching during prepareForCommit

This patch fixes a crash caused by a frame losing both its DocumentLoaders.
When the main document loader is detached, various subresources can hook
into 'abort' and try to stop the provisional load that is about to commit.
This causes both document loaders to be detached, and the frame to be in a
non-detached limbo state.

BUG=394055

Review URL: https://codereview.chromium.org/1714063002

Cr-Commit-Position: refs/heads/master@{#377900}