Migrate HostZoomMap to live in StoragePartition.

content/browser/host_zoom_level_context.h

+// Copyright (c) 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_BROWSER_HOST_ZOOM_LEVEL_CONTEXT_H_
+#define CONTENT_BROWSER_HOST_ZOOM_LEVEL_CONTEXT_H_
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "content/browser/host_zoom_map_impl.h"
+#include "content/public/browser/zoom_level_delegate.h"
+
+class PrefService;
+
+namespace base {
+class FilePath;
+}
+
+namespace content {
+struct HostZoomLevelContextDeleter;
+
+// This class manages a HostZoomMap and, associates it with a PrefsStore,
+// if one is provided. It also serves to keep the zoom level machinery details
+// deparate from the owning StoragePartitionImpl.
+class HostZoomLevelContext
+    : public base::RefCountedThreadSafe<HostZoomLevelContext,
+                                        HostZoomLevelContextDeleter> {

[Fady Samuel, 2014/11/03 22:11:11]

Is the HostZoomLevelContextDeleter necessary?

[wjmaclean, 2014/11/04 19:34:25]

After a quick experiment, apparently no! Good to know ...

+ public:
+  HostZoomLevelContext(scoped_ptr<ZoomLevelDelegate> zoom_level_delegate,
+                       const base::FilePath& file_path);
+
+  HostZoomMap* GetHostZoomMap() const { return host_zoom_map_impl_.get(); }
+  ZoomLevelDelegate* GetZoomLevelDelegate() const {
+    return zoom_level_delegate_.get();
+  }
+
+ protected:
+  virtual ~HostZoomLevelContext();
+
+ private:
+  friend class base::DeleteHelper<HostZoomLevelContext>;
+  friend class base::RefCountedThreadSafe<HostZoomLevelContext,
+                                          HostZoomLevelContextDeleter>;
+  friend struct HostZoomLevelContextDeleter;
+
+  void DeleteOnCorrectThread() const;
+
+  scoped_ptr<HostZoomMapImpl> host_zoom_map_impl_;
+  // The prefs_store pointer needs to be released before the destructor for the

[wjmaclean, 2014/11/03 22:11:06]

This comment is stale, I'll remove it in the next CL.

[Fady Samuel, 2014/11/03 22:11:11]

nit: don't mention prefs in content.

+  // HostZoomMapImpl is called, and so must be declared in this order.
+  scoped_ptr<ZoomLevelDelegate> zoom_level_delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(HostZoomLevelContext);
+};
+
+struct HostZoomLevelContextDeleter {
+  static void Destruct(const HostZoomLevelContext* context) {
+    context->DeleteOnCorrectThread();
+  }
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_HOST_ZOOM_LEVEL_CONTEXT_H_