Diagnose RenderFrameImpl::didCommitProvisionalLoad crash.

These temporary crash keys should reveal whether the RenderView has
changed or been deleted between the local-to-remote swap and the
remote-to-local commit.

BUG=575245
TEST=New crash keys present in crash reports.

Review URL: https://codereview.chromium.org/1613453002

Cr-Commit-Position: refs/heads/master@{#370522}
2 files changed