Introduce ChromeZoomLevelPref, make zoom level prefs independent of profile prefs.

chrome/browser/ui/zoom/chrome_zoom_level_prefs.h

+// Copyright (c) 2014 The Chromium Authors. All rights reserved.

[sky, 2014/10/10 19:43:59]

nit: style guide says don't use the (c) for new files.

[wjmaclean, 2014/10/10 20:23:02]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_UI_ZOOM_CHROME_ZOOM_LEVEL_PREFS_H_
+#define CHROME_BROWSER_UI_ZOOM_CHROME_ZOOM_LEVEL_PREFS_H_
+
+#include "base/callback.h"
+#include "base/files/file_path.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/observer_list.h"
+#include "base/prefs/json_pref_store.h"
+#include "base/prefs/pref_change_registrar.h"
+#include "base/prefs/pref_service.h"
+#include "base/prefs/pref_store.h"
+#include "content/public/browser/host_zoom_map.h"
+
+namespace base {
+class DictionaryValue;
+}
+
+namespace chrome {
+
+// A class to manage per-partition default and per-host zoom levels in Chrome's
+// preference system. It implements an interface between the content/ zoom
+// levels in HostZoomMap and Chrome's preference persistence system. All changes

[sky, 2014/10/10 19:43:59]

nit: preferences imply persistence. I don't think you need to say persistence
here.

[wjmaclean, 2014/10/10 20:23:02]

Done.

+// to the per-partition default zoom levels from chrome/ flow through this
+// class. Any changes to per-host levels are updated when HostZoomMap calls
+// OnZoomLevelChanged.
+class ChromeZoomLevelPrefs {

[sky, 2014/10/10 19:43:59]

Is there a reason you don't have a unit test for this file? Is it covered by
other tests?

[wjmaclean, 2014/10/10 20:23:02]

Yes, through HostZoomMap browser tests, and any other browser test that involves
zoom functionality. A specific HostZoomMap browser test is included to test the
migration aspect (and is the reason for the GetHashForTesting() function.

+ public:
+  typedef base::CallbackList<void(void)>::Subscription
+      DefaultZoomLevelSubscription;
+
+  // Exposed as static function for testing.
+  static std::string GetHash(const base::FilePath& relative_path);

[sky, 2014/10/10 19:43:59]

GetHasForTesting.

[sky, 2014/10/10 19:43:59]

nit: constructor/destructor before any other functions.

[wjmaclean, 2014/10/10 20:23:02]

Done. But it's also used internally in the class, is that OK? It looks a little
weird there. I suppose we could add an internal function GetHash() and an
external accessor named GetHashForTesting, if that's not overkill?

[wjmaclean, 2014/10/10 20:23:02]

Done.

Sorry, I thought static functions went first, but I should have checked.

+
+  // Initialize the pref_service and the profile_path via the constructor,
+  // as these concepts won't be available in the content base class
+  // (to be added later) which will define the InitPrefsAndCopyToHostZoomMap
+  // interface. |pref_service_| must outlive this class.
+  ChromeZoomLevelPrefs(PrefService* pref_service,
+                       const base::FilePath& profile_path);
+  virtual ~ChromeZoomLevelPrefs();
+
+  virtual void InitPrefsAndCopyToHostZoomMap(
+      const base::FilePath& partition_path,
+      content::HostZoomMap* host_zoom_map);
+
+  void SetDefaultZoomLevelPref(double level);
+  double GetDefaultZoomLevelPref() const;
+  scoped_ptr<DefaultZoomLevelSubscription> RegisterDefaultZoomLevelCallback(
+      const base::Closure& callback);
+
+  void ExtractPerHostZoomLevels(
+      const base::DictionaryValue* host_zoom_dictionary);
+
+ private:
+  // 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_;
+  base::FilePath profile_path_;

[sky, 2014/10/10 19:43:59]

nit: const.

[wjmaclean, 2014/10/10 20:23:02]

Done.

+  content::HostZoomMap* host_zoom_map_;
+  scoped_ptr<content::HostZoomMap::Subscription> zoom_subscription_;
+  std::string partition_key_;
+  base::CallbackList<void(void)> default_zoom_changed_callbacks_;
+
+  DISALLOW_COPY_AND_ASSIGN(ChromeZoomLevelPrefs);
+};
+
+}  // namespace chrome
+
+#endif  // CHROME_BROWSER_UI_ZOOM_CHROME_ZOOM_LEVEL_PREFS_H_