Merge "Fix deadlock of WebViewCoreThread"

        // in the UI thread. The WebViewClient and WebChromeClient functions

        // that check for a non-null callback are ok because java ensures atomic

        // 32-bit reads and writes.

        if (messagesBlocked()) return;

        if (messagesBlocked()) {

            synchronized (this) {

                notify();

            }

            return;

        }

        switch (msg.what) {

            case PAGE_STARTED:

                String startedUrl = msg.getData().getString("url");