PlzNavigate: set the right cache policy on back POST navigations

content/browser/frame_host/navigation_request.cc

Index: content/browser/frame_host/navigation_request.cc
diff --git a/content/browser/frame_host/navigation_request.cc b/content/browser/frame_host/navigation_request.cc
index 78feda7b14b01e63c73835236b173c8a1a6770ac..cce181790f1f4e754e5879a56fc161e95326eae1 100644
--- a/content/browser/frame_host/navigation_request.cc
+++ b/content/browser/frame_host/navigation_request.cc
@@ -75,11 +75,16 @@ void UpdateLoadFlagsWithCacheFlags(
       break;
     case FrameMsg_Navigate_Type::SAME_DOCUMENT:
     case FrameMsg_Navigate_Type::DIFFERENT_DOCUMENT:
-    case FrameMsg_Navigate_Type::HISTORY_SAME_DOCUMENT:
-    case FrameMsg_Navigate_Type::HISTORY_DIFFERENT_DOCUMENT:
       if (is_post)
         *load_flags |= net::LOAD_VALIDATE_CACHE;
       break;
+    case FrameMsg_Navigate_Type::HISTORY_SAME_DOCUMENT:
+    case FrameMsg_Navigate_Type::HISTORY_DIFFERENT_DOCUMENT:
+      if (is_post) {
+        *load_flags |=
+            net::LOAD_ONLY_FROM_CACHE | net::LOAD_SKIP_CACHE_VALIDATION;
+      }
+      break;
   }
 }