Add setting to isolate zoom changes by default.

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 a6f312579bf1e2d3b42d98bc1446d0f4db972ade..f050211ada86f2e876018aab767520a78b65ec26 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -1115,6 +1115,11 @@ const char kPartitionDefaultZoomLevel[] = "partition.default_zoom_level";
 // be displayed at the default zoom level.
 const char kPartitionPerHostZoomLevels[] = "partition.per_host_zoom_levels";
 
+// Whether zoom changes should be scoped to origins by default.
+// If false, zoom changes are per-tab.
+const char kPartitionZoomScopeIsPerOrigin[] =
+    "partition.zoom_scope_is_per_origin";
+
 #if !defined(OS_ANDROID)
 const char kPinnedTabs[] = "pinned_tabs";
 #endif