AW: add boundary interfaces for new classes used in callbacks This adds boundary interfaces for SafeBrowsingResponse and WebResourceError, both of which are post-L classes added in WebViewClient callbacks (onSafeBrowsingHit() and onReceivedError()). Design doc: http://go/wv-support-library-callbacks Bug: 781764 Test: N/A Change-Id: Idcf1b4af21b197f951192b5a262f63ec0500debe Reviewed-on: https://chromium-review.googlesource.com/982651 Reviewed-by: Richard Coles <[email protected]> Commit-Queue: Nate Fischer <[email protected]> Cr-Original-Commit-Position: refs/heads/master@{#546590} Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src Cr-Mirrored-Commit: b73c062f19bf41d9f50c405302b9bdfe419b554d