Split infobar_delegate.[cc,h] into separate pieces for the different classes defined within, so that

chrome/browser/tab_contents/link_infobar_delegate.cc

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/tab_contents/link_infobar_delegate.h"
+
+#include "content/browser/tab_contents/tab_contents.h"
+
+bool LinkInfoBarDelegate::LinkClicked(WindowOpenDisposition disposition) {
+  return true;
+}
+
+LinkInfoBarDelegate::LinkInfoBarDelegate(TabContents* contents)
+    : InfoBarDelegate(contents) {
+}
+
+LinkInfoBarDelegate::~LinkInfoBarDelegate() {
+}
+
+LinkInfoBarDelegate* LinkInfoBarDelegate::AsLinkInfoBarDelegate() {
+  return this;
+}