[NotLanded] Implement the fetching algorithm of the Web Manifest.

Source/core/fetch/Resource.cpp

Index: Source/core/fetch/Resource.cpp
diff --git a/Source/core/fetch/Resource.cpp b/Source/core/fetch/Resource.cpp
index ff898e2a129f2decc402aee403328c16bf45330b..7d81c12fe0ca030d382669682cf831d8efc35e98 100644
--- a/Source/core/fetch/Resource.cpp
+++ b/Source/core/fetch/Resource.cpp
@@ -938,6 +938,8 @@ static const char* initatorTypeNameToString(const AtomicString& initiatorTypeNam
         return "Internal resource";
     if (initiatorTypeName == FetchInitiatorTypeNames::link)
         return "Link element resource";
+    if (initiatorTypeName == FetchInitiatorTypeNames::manifest)
+        return "Manifest";
     if (initiatorTypeName == FetchInitiatorTypeNames::processinginstruction)
         return "Processing instruction";
     if (initiatorTypeName == FetchInitiatorTypeNames::texttrack)
@@ -979,6 +981,8 @@ const char* Resource::resourceTypeToString(Type type, const FetchInitiatorInfo&
         return "Imported resource";
     case Resource::Media:
         return "Media";
+    case Resource::Manifest:
+        return "Manifest";
     }
     ASSERT_NOT_REACHED();
     return initatorTypeNameToString(initiatorInfo.name);
@@ -1014,6 +1018,8 @@ const char* ResourceTypeName(Resource::Type type)
         return "ImportResource";
     case Resource::Media:
         return "Media";
+    case Resource::Manifest:
+        return "Manifest";
     }
     ASSERT_NOT_REACHED();
     return "Unknown";