GitLab

Notable changes:
 * CRWWebViewProxyImpl now uses synthesized getter and ivar for
property contentView
 * CRWJSPOSTRequestLoader now does not create a retain cycle of
CRWWKScriptMessageRouter objects. The cycle seems to have been harmless,
but it definitely brings no value, and it's better to not have it.

BUG=651830

Review-Url: https://codereview.chromium.org/2380323002
Cr-Commit-Position: refs/heads/master@{#422776}