Reland: Communicate ExtensionSettings policy to renderers

extensions/common/extension.h

Index: extensions/common/extension.h
diff --git a/extensions/common/extension.h b/extensions/common/extension.h
index 97c0ca6eb3b0fc09393e71a91de75064b5ac06a5..b87cc5f2dd89f1c6962631c25306fdb08d0dee98 100644
--- a/extensions/common/extension.h
+++ b/extensions/common/extension.h
@@ -542,6 +542,7 @@ struct UpdatedExtensionPermissionsInfo {
   enum Reason {
     ADDED,    // The permissions were added to the extension.
     REMOVED,  // The permissions were removed from the extension.
+    POLICY,   // The policy that affects permissions was updated.
   };
 
   Reason reason;