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

chrome/browser/ui/zoom/zoom_level_prefs_store_impl.h

Index: chrome/browser/ui/zoom/zoom_level_prefs_store_impl.h
diff --git a/chrome/browser/ui/zoom/zoom_level_prefs_store_impl.h b/chrome/browser/ui/zoom/zoom_level_prefs_store_impl.h
new file mode 100644
index 0000000000000000000000000000000000000000..0d686a3fc74e40b4edcdc0f5e3f8160659512010
--- /dev/null
+++ b/chrome/browser/ui/zoom/zoom_level_prefs_store_impl.h
@@ -0,0 +1,57 @@
+// 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 CHROME_BROWSER_UI_ZOOM_ZOOM_LEVEL_PREFS_STORE_IMPL_H_
+#define CHROME_BROWSER_UI_ZOOM_ZOOM_LEVEL_PREFS_STORE_IMPL_H_
+
+#include "content/public/browser/zoom_level_prefs_store.h"
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/prefs/json_pref_store.h"
+#include "base/prefs/pref_store.h"
+#include "chrome/browser/prefs/pref_service_syncable.h"
+#include "content/public/browser/host_zoom_map.h"
+
+namespace chrome {
+
+// A class to implement ZoomLevelPrefsStore. It also implements
+// PrefStore::Observer so that it can track changes to the prefs.
+// Finally, the prefs are also updated in response to zoom events
+// from HostZoomMap.
+class ZoomLevelPrefsStoreImpl : public PrefStore::Observer,
+                                public content::ZoomLevelPrefsStore {
+ public:
+  ZoomLevelPrefsStoreImpl();
+  virtual ~ZoomLevelPrefsStoreImpl();
+
+  // Implement ZoomLevelPrefsStore.

[Peter Kasting, 2014/09/11 00:45:48]

Tiny nit: I'd make these comments look like "// content::ZoomLevelPrefsStore:",
which is about as short as possible and matches the superclass name exactly.

Also, generally try to give override blocks in the same order as the actual
superclasses are listed above.

[wjmaclean, 2014/09/11 21:00:51]

Done.

+  virtual void InitPrefsAndCopyToHostZoomMap(
+      const base::FilePath& file_path,
+      content::HostZoomMap* host_zoom_map) OVERRIDE;
+  virtual PrefService* GetPrefs() OVERRIDE;
+
+  // Implement PrefObserver.
+  virtual void OnPrefValueChanged(const std::string& key) OVERRIDE;
+  virtual void OnInitializationCompleted(bool succeeded) OVERRIDE;
+
+  // TODO(wjmaclean): remove this when migration is complete.
+  virtual void SetInitCallback(const base::Closure& callback);
+
+ private:
+  void OnZoomLevelChanged(const content::HostZoomMap::ZoomLevelChange& change);
+
+  base::Closure callback_;
+  scoped_refptr<JsonPrefStore> zoom_level_prefs_;
+  scoped_ptr<PrefServiceSyncable> pref_service_;
+  scoped_ptr<content::HostZoomMap::Subscription> zoom_subscription_;
+  content::HostZoomMap* host_zoom_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(ZoomLevelPrefsStoreImpl);
+};
+
+}  // namespace chrome
+
+#endif  // CHROME_BROWSER_UI_ZOOM_ZOOM_LEVEL_PREFS_STORE_IMPL_H_