Make WebView no operation when render process died

BUG=666106

Review-Url: https://codereview.chromium.org/2643333003
Cr-Commit-Position: refs/heads/master@{#445410}
(cherry picked from commit f85d298)

Review-Url: https://codereview.chromium.org/2651563006 .
Cr-Commit-Position: refs/branch-heads/2987@{#53}
Cr-Branched-From: ad51088-refs/heads/master@{#444943}