Migrate HostZoomMap to live in StoragePartition.

content/public/browser/zoom_level_delegate.h

+// Copyright 2014 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.
+
+#ifndef CONTENT_PUBLIC_BROWSER_ZOOM_LEVEL_DELEGATE_H_
+#define CONTENT_PUBLIC_BROWSER_ZOOM_LEVEL_DELEGATE_H_
+
+namespace content {
+
+class HostZoomMap;
+
+// An interface to allow the client to initialize the HostZoomMap.
+class ZoomLevelDelegate {
+ public:
+  virtual void InitHostZoomMap(HostZoomMap* host_zoom_map) = 0;
+  virtual ~ZoomLevelDelegate() {}
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_BROWSER_ZOOM_LEVEL_DELEGATE_H_