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

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 173ee911ccc510dcaaeb5759e8ceef77474e8ba0..969f1995e6be6d204e3a3aacb94442b2388f66e6 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -1028,11 +1028,16 @@ const char kBlockThirdPartyCookies[] = "profile.block_third_party_cookies";
 const char kClearSiteDataOnExit[] = "profile.clear_site_data_on_exit";
 
 // Double that indicates the default zoom level.
-const char kDefaultZoomLevel[] = "profile.default_zoom_level";
+const char kPartitionDefaultZoomLevel[] = "partition.default_zoom_level";
+// TODO(wjmaclean): Remove this once sufficient users have migrated to the
+// per-StoragePartition zoom levels. http://crbug.com/420643.
+const char kDefaultZoomLevelDeprecated[] = "profile.default_zoom_level";
 
 // Dictionary that maps hostnames to zoom levels.  Hosts not in this pref will
 // be displayed at the default zoom level.
-const char kPerHostZoomLevels[] = "profile.per_host_zoom_levels";
+const char kPartitionPerHostZoomLevels[] = "partition.per_host_zoom_levels";
+// TODO(wjmaclean): Remove this.
+const char kPerHostZoomLevelsDeprecated[] = "profile.per_host_zoom_levels";
 
 // A dictionary that tracks the default data model to use for each section of
 // the dialog.