And to answer your question about the <base>
tag being supported in Chrome: it is. I created a simple HTML document:
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-type" content="text/html; charset=UTF-8">
<base href="http://google.com">
<title>Testing base-tag</title>
</head>
<body>
<img src="/intl/en_ALL/images/logo.gif">
</body>
</html>
which is rendered correctly.
EDIT: PROBLEM PROBABLY DISCOVERED
I searched the Chromium bugs page for "base tag" and found two (probably the same) bugs about your problem, i.e. issue 25090 and 32134.
I suggest you file a comment in one of those (after deleting the forbidden end tag of <base>) and hope this problem is resolved soon.
EDIT 2: I made another test case and commented in this bug report.
EDIT 3: Bug seems to be resolved after upgrading to Chrome 4.0.249.89.