Show service worker navigation preload requests in DevTools Network tab

third_party/WebKit/Source/core/inspector/browser_protocol.json

 {
     "version": { "major": "1", "minor": "2" },
     "domains": [{
         "domain": "Inspector",
         "experimental": true,
         "types": [],
         "commands": [
             {
                 "name": "enable",
                 "description": "Enables inspector domain notifications."
@@ skipping 1092 matching lines @@
                     { "name": "type", "$ref": "Page.ResourceType", "description": "Type of this resource." },
                     { "name": "response", "$ref": "Response", "optional": true, "description": "Cached response data." },
                     { "name": "bodySize", "type": "number", "description": "Cached response body size." }
                 ]
             },
             {
                 "id": "Initiator",
                 "type": "object",
                 "description": "Information about the request initiator.",
                 "properties": [
-                    { "name": "type", "type": "string", "enum": ["parser", "script", "other"], "description": "Type of this initiator." },
+                    { "name": "type", "type": "string", "enum": ["parser", "script", "preload", "other"], "description": "Type of this initiator." },
                     { "name": "stack", "$ref": "Runtime.StackTrace", "optional": true, "description": "Initiator JavaScript stack trace, set for Script only." },
                     { "name": "url", "type": "string", "optional": true, "description": "Initiator URL, set for Parser type only." },
                     { "name": "lineNumber", "type": "number", "optional": true, "description": "Initiator line number, set for Parser type only (0-based)." }
                 ]
             },
             {
                 "id": "Cookie",
                 "type": "object",
                 "description": "Cookie object",
                 "properties": [
@@ skipping 3371 matching lines @@
                 "name": "accepted",
                 "description": "Informs that port was successfully bound and got a specified connection id.",
                 "parameters": [
                     {"name": "port", "type": "integer", "description": "Port number that was successfully bound." },
                     {"name": "connectionId", "type": "string", "description": "Connection id to be used." }
                 ]
             }
         ]
     }]
 }