Move referrer policy to a different field when serializing.

components/sessions/ios/ios_serialized_navigation_driver.cc

Index: components/sessions/ios/ios_serialized_navigation_driver.cc
diff --git a/components/sessions/ios/ios_serialized_navigation_driver.cc b/components/sessions/ios/ios_serialized_navigation_driver.cc
index f6324ab35fb00a1e3413c2ea6a0362798f418380..3c1ec1ec88896c47f043d6a36384ba7c68047571 100644
--- a/components/sessions/ios/ios_serialized_navigation_driver.cc
+++ b/components/sessions/ios/ios_serialized_navigation_driver.cc
@@ -32,6 +32,41 @@ int IOSSerializedNavigationDriver::GetDefaultReferrerPolicy() const {
   return web::ReferrerPolicyDefault;
 }
 
+bool IOSSerializedNavigationDriver::MapReferrerPolicyToOldValues(
+    int referrer_policy,
+    int* mapped_referrer_policy) const {
+  // "always" and "default" are the same value in all versions.
+  if (referrer_policy == web::ReferrerPolicyAlways ||
+      referrer_policy == web::ReferrerPolicyDefault) {
+    *mapped_referrer_policy = referrer_policy;
+    return true;
+  }
+
+  // "origin" exists in the old encoding.
+  if (referrer_policy == web::ReferrerPolicyOrigin) {
+    *mapped_referrer_policy = 3;
+    return true;
+  }
+
+  // Everything else is mapped to never.
+  *mapped_referrer_policy = 2;
+  return false;
+}
+
+bool IOSSerializedNavigationDriver::MapReferrerPolicyToNewValues(
+    int referrer_policy,
+    int* mapped_referrer_policy) const {
+  // "always" and "default" are the same value in all versions.
+  if (referrer_policy == 0 || referrer_policy == 1) {
+    *mapped_referrer_policy = referrer_policy;
+    return true;
+  }
+
+  // Since we don't know what encoding was used, we map the rest to "never".
+  *mapped_referrer_policy = web::ReferrerPolicyNever;
+  return false;
+}
+
 std::string
 IOSSerializedNavigationDriver::GetSanitizedPageStateForPickle(
     const SerializedNavigationEntry* navigation) const {
@@ -48,13 +83,20 @@ void IOSSerializedNavigationDriver::Sanitize(
       !referrer.url.SchemeIsHTTPOrHTTPS()) {
     referrer.url = GURL();
   } else {
+    if (referrer.policy < 0 || referrer.policy > web::ReferrerPolicyLast) {
+      NOTREACHED();
+      referrer.policy = web::ReferrerPolicyNever;
+    }
+    bool is_downgrade = referrer.url.SchemeIsSecure() &&
+                        !navigation->virtual_url_.SchemeIsSecure();
     switch (referrer.policy) {
       case web::ReferrerPolicyDefault:
-        if (referrer.url.SchemeIsSecure() &&
-            !navigation->virtual_url_.SchemeIsSecure()) {
+        if (is_downgrade)
           referrer.url = GURL();
-        }
         break;
+      case web::ReferrerPolicyNoReferrerWhenDowngrade:
+        if (is_downgrade)
+          referrer.url = GURL();
       case web::ReferrerPolicyAlways:
         break;
       case web::ReferrerPolicyNever:
@@ -63,8 +105,9 @@ void IOSSerializedNavigationDriver::Sanitize(
       case web::ReferrerPolicyOrigin:
         referrer.url = referrer.url.GetOrigin();
         break;
-      default:
-        NOTREACHED();
+      case web::ReferrerPolicyOriginWhenCrossOrigin:
+        if (navigation->virtual_url_.GetOrigin() != referrer.url.GetOrigin())
+          referrer.url = referrer.url.GetOrigin();
         break;
     }
   }