No longer register app window placement preference keys on the fly.

chrome/browser/prefs/browser_ui_prefs_migrator.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 CHROME_BROWSER_PREFS_BROWSER_UI_PREFS_MIGRATOR_H_
+#define CHROME_BROWSER_PREFS_BROWSER_UI_PREFS_MIGRATOR_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "base/prefs/pref_store.h"
+#include "base/prefs/writeable_pref_store.h"
+
+// When prefs are loaded from disk this class migrates some previously
+// dynamically registered preferences to their new home in a statically
+// registered dictionary. It can't follow the usual migration pattern because
+// it is migrating preferences that aren't registered at migration time and has
+// to iterate over a raw DictionaryValue looking for keys to migrate.
+//
+// Objects of this class delete themselves after the migration.
+//
+// TODO(dgrogan): Delete this for m41. See http://crbug.com/167256.
+
+class BrowserUIPrefsMigrator : public PrefStore::Observer {
+ public:
+  explicit BrowserUIPrefsMigrator(WriteablePrefStore* pref_store);
+
+  // Overrides from PrefStore::Observer.
+  virtual void OnPrefValueChanged(const std::string& key) OVERRIDE {}
+  virtual void OnInitializationCompleted(bool succeeded) OVERRIDE;
+
+ private:
+  friend struct base::DefaultDeleter<BrowserUIPrefsMigrator>;
+
+  virtual ~BrowserUIPrefsMigrator();
+
+  WriteablePrefStore* pref_store_;
+
+  DISALLOW_COPY_AND_ASSIGN(BrowserUIPrefsMigrator);
+};
+
+#endif  // CHROME_BROWSER_PREFS_BROWSER_UI_PREFS_MIGRATOR_H_