Remove dangling LeakExpectations pointers.
Remove dangling LeakExpectations pointers.

TBR=kouhei,yutak@chromium.org
BUG=364411,364417,506754
NOTRY=true

Review URL: https://codereview.chromium.org/1771943003

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#379793}

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk