Support requesting subsets of host permissions using the permissions API.

chrome/common/extensions/permissions/permission_set.h

Index: chrome/common/extensions/permissions/permission_set.h
diff --git a/chrome/common/extensions/permissions/permission_set.h b/chrome/common/extensions/permissions/permission_set.h
index a2e3d10b24d15c0479b73f1addd079b4b0ea3afa..11e6bae60ec46e636494dfbbd631820bf009b919 100644
--- a/chrome/common/extensions/permissions/permission_set.h
+++ b/chrome/common/extensions/permissions/permission_set.h
@@ -70,6 +70,12 @@ class PermissionSet
   // Returns true if |set| is a subset of this.
   bool Contains(const PermissionSet& set) const;
 
+  // Returns true if the API permissions in |set| are a subset of this, and the
+  // host permissions in this encompass those in |set|.
+  //
+  // See URLPatternSet::Encompasses for more info.
+  bool ContainsOrEncompasses(const PermissionSet& set) const;
+
   // Gets the API permissions in this set as a set of strings.
   std::set<std::string> GetAPIsAsStrings() const;