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

chrome/browser/prefs/chrome_pref_service_factory.cc

Index: chrome/browser/prefs/chrome_pref_service_factory.cc
diff --git a/chrome/browser/prefs/chrome_pref_service_factory.cc b/chrome/browser/prefs/chrome_pref_service_factory.cc
index 81b2c6670c8f92deaf05cf5067846753f6acb13f..d741a7d5f258ec669484b4ec697a6432d94e4621 100644
--- a/chrome/browser/prefs/chrome_pref_service_factory.cc
+++ b/chrome/browser/prefs/chrome_pref_service_factory.cc
@@ -35,6 +35,7 @@
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/search_engines/default_search_pref_migration.h"
 #include "chrome/browser/sync/glue/sync_start_util.h"
+#include "chrome/browser/ui/prefs_migrator.h"
 #include "chrome/browser/ui/profile_error_dialog.h"
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/pref_names.h"
@@ -463,14 +464,19 @@ scoped_ptr<PrefServiceSyncable> CreateProfilePrefs(
                  syncer::PREFERENCES);
 
   PrefServiceSyncableFactory factory;
+  scoped_refptr<PersistentPrefStore> user_pref_store(
+      CreateProfilePrefStoreManager(profile_path)
+          ->CreateProfilePrefStore(pref_io_task_runner,
+                                   start_sync_flare_for_prefs,
+                                   validation_delegate));
+  // BrowserUIPrefsMigrationObserver unregisters and deletes itself after it is
+  // done migrating.
+  user_pref_store->AddObserver(
+      new BrowserUIPrefsMigrationObserver(user_pref_store));
   PrepareFactory(&factory,
                  policy_service,
                  supervised_user_settings,
-                 scoped_refptr<PersistentPrefStore>(
-                     CreateProfilePrefStoreManager(profile_path)
-                         ->CreateProfilePrefStore(pref_io_task_runner,
-                                                  start_sync_flare_for_prefs,
-                                                  validation_delegate)),
+                 user_pref_store,
                  extension_prefs,
                  async);
   scoped_ptr<PrefServiceSyncable> pref_service =