Add missing Referrer Policies

  * Add same-origin, strict-origin and strict-origin-when-cross-origin

Author: jeremydurham

lib/secure_headers/headers/referrer_policy.rb

@@ -6,6 +6,9 @@ class ReferrerPolicy
     VALID_POLICIES = %w(
       no-referrer
       no-referrer-when-downgrade
+      same-origin
+      strict-origin
+      strict-origin-when-cross-origin
       origin
       origin-when-cross-origin
       unsafe-url

spec/lib/secure_headers/headers/referrer_policy_spec.rb

@@ -18,6 +18,24 @@ module SecureHeaders
         end.not_to raise_error
       end
 
+      it "accepts 'same-origin'" do
+        expect do
+          ReferrerPolicy.validate_config!("same-origin")
+        end.not_to raise_error
+      end
+
+      it "accepts 'strict-origin'" do
+        expect do
+          ReferrerPolicy.validate_config!("strict-origin")
+        end.not_to raise_error
+      end
+
+      it "accepts 'strict-origin-when-cross-origin'" do
+        expect do
+          ReferrerPolicy.validate_config!("strict-origin-when-cross-origin")
+        end.not_to raise_error
+      end
+
       it "accepts 'origin'" do
         expect do
           ReferrerPolicy.validate_config!("origin")