Add prefetch support to AffiliationBackend.

components/password_manager/core/browser/affiliation_utils.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file contains utilities related to working with "facets".
 //
 // A "facet" is defined as the manifestation of a logical application on a given
 // platform. For example, "My Bank" may have released an Android application
 // and a Web application accessible from a browser. These are all facets of the
 // "My Bank" logical application.
@@ skipping 88 matching lines @@
 
   // Returns whether or not this instance represents a valid facet identifier
   // referring to a Web application.
   bool IsValidWebFacetURI() const;
 
   // Returns whether or not this instance represents a valid facet identifier
   // referring to an Android application.
   bool IsValidAndroidFacetURI() const;
 
   // Returns whether or not this instance represents a valid facet identifier
-  // referring to either a Web or an Android application.
+  // referring to either a Web or an Android application. The empty identfier is
+  // not considered valid.
   bool is_valid() const { return is_valid_; }
 
+  // Returns whether or not this instance represents the empty facet identifier.
+  bool is_empty() const { return canonical_spec_.empty(); }
+
   // Returns the canonical scheme of the encapsulated facet URI, provided it is
   // valid, or the empty string otherwise.
   std::string scheme() const;
 
   // Returns the canonical package name that the encapsulated facet URI
   // references, provided it is a valid Android facet URI, or the empty string
   // otherwise.
   std::string android_package_name() const;
 
   // Returns the text of the encapsulated canonical URI, which must be valid.
@@ skipping 62 matching lines @@
 template <>
 struct hash<password_manager::FacetURI> {
   size_t operator()(const password_manager::FacetURI& facet_uri) const {
     return hash<std::string>()(facet_uri.potentially_invalid_spec());
   }
 };
 
 }  // namespace BASE_HASH_NAMESPACE
 
 #endif  // COMPONENTS_PASSWORD_MANAGER_CORE_BROWSER_AFFILIATION_UTILS_H_