refactor: move media/net from brightray to atom (#15288)

atom/browser/zoom_level_delegate.h

@@ -0,0 +1,64 @@
+// 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 ATOM_BROWSER_ZOOM_LEVEL_DELEGATE_H_
+#define ATOM_BROWSER_ZOOM_LEVEL_DELEGATE_H_
+
+#include <memory>
+#include <string>
+
+#include "base/files/file_path.h"
+#include "base/macros.h"
+#include "components/prefs/pref_service.h"
+#include "content/public/browser/host_zoom_map.h"
+#include "content/public/browser/zoom_level_delegate.h"
+
+namespace base {
+class DictionaryValue;
+}
+
+class PrefRegistrySimple;
+
+namespace atom {
+
+// A class to manage per-partition default and per-host zoom levels.
+// It implements an interface between the content/ zoom
+// levels in HostZoomMap and preference system. All changes
+// to the per-partition default zoom levels flow through this
+// class. Any changes to per-host levels are updated when HostZoomMap calls
+// OnZoomLevelChanged.
+class ZoomLevelDelegate : public content::ZoomLevelDelegate {
+ public:
+  static void RegisterPrefs(PrefRegistrySimple* pref_registry);
+
+  ZoomLevelDelegate(PrefService* pref_service,
+                    const base::FilePath& partition_path);
+  ~ZoomLevelDelegate() override;
+
+  void SetDefaultZoomLevelPref(double level);
+  double GetDefaultZoomLevelPref() const;
+
+  // content::ZoomLevelDelegate:
+  void InitHostZoomMap(content::HostZoomMap* host_zoom_map) override;
+
+ private:
+  void ExtractPerHostZoomLevels(
+      const base::DictionaryValue* host_zoom_dictionary);
+
+  // This is a callback function that receives notifications from HostZoomMap
+  // when per-host zoom levels change. It is used to update the per-host
+  // zoom levels (if any) managed by this class (for its associated partition).
+  void OnZoomLevelChanged(const content::HostZoomMap::ZoomLevelChange& change);
+
+  PrefService* pref_service_;
+  content::HostZoomMap* host_zoom_map_;
+  std::unique_ptr<content::HostZoomMap::Subscription> zoom_subscription_;
+  std::string partition_key_;
+
+  DISALLOW_COPY_AND_ASSIGN(ZoomLevelDelegate);
+};
+
+}  // namespace atom
+
+#endif  // ATOM_BROWSER_ZOOM_LEVEL_DELEGATE_H_