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

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index 431de5a7a64924afcccae1eb96b9c03748b19f37..1e0e7f597a3c35e65c09329c82ce09ec67a5b836 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -1421,6 +1421,10 @@ const char kBrowserWindowPlacementPopup[] = "browser.window_placement_popup";
 // manager window to restore on startup.
 const char kTaskManagerWindowPlacement[] = "task_manager.window_placement";
 
+// A collection of position, size, and other data relating to app windows to
+// restore on startup.
+const char kAppWindowPlacement[] = "browser.app_window_placement";
+
 // An integer specifying the total number of bytes to be used by the
 // renderer's in-memory cache of objects.
 const char kMemoryCacheSize[] = "renderer.memory_cache.size";