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", "$ref": "Runtime.StackTrace", "optional": true, "description": "Initiator JavaScript stack trace, set for Script only." },
                     { "name": "url", "type": "string", "optional": true, "description": "Initiator URL, set for Parser type only." },
                     { "name": "lineNumber", "type": "number", "optional": true, "description": "Initiator line number, set for Parser type only (0-based)." }
                 ]
             },
             {
                 "id": "Cookie",
                 "type": "object",
                 "description": "Cookie object",
                 "properties": [
@@ skipping 353 matching lines @@
                 "name": "eventSourceMessageReceived",
                 "description": "Fired when EventSource message is received.",
                 "parameters": [
                     { "name": "requestId", "$ref": "RequestId", "description": "Request identifier." },
                     { "name": "timestamp", "$ref": "Timestamp", "description": "Timestamp." },
                     { "name": "eventName", "type": "string", "description": "Message type." },
                     { "name": "eventId", "type": "string", "description": "Message identifier." },
                     { "name": "data", "type": "string", "description": "Message content." }
                 ],
                 "experimental": true
+            },
+            {
+                "name": "navigationPreloadSent",
+                "description": "Fired when FetchEvent which has triggered a navigation preload request is received.",
+                "parameters": [
+                    { "name": "requestId", "$ref": "RequestId", "description": "Request identifier." },
+                    { "name": "url", "type": "string", "description": "Navigation preload request URL." },
+                    { "name": "timestamp", "$ref": "Timestamp", "description": "Timestamp." },
+                    { "name": "wallTime", "$ref": "Timestamp", "description": "UTC Timestamp." },
+                    { "name": "initiator", "$ref": "Initiator", "description": "Request initiator." }
+                ],
+                "experimental": true
+            },
+            {
+                "name": "navigationPreloadResponseReceived",
+                "description": "Fired when navigation preload response is available.",
+                "parameters": [
+                    { "name": "requestId", "$ref": "RequestId", "description": "Request identifier." },
+                    { "name": "timestamp", "$ref": "Timestamp", "description": "Timestamp." },
+                    { "name": "response", "$ref": "Response", "description": "Response data." }
+                ],
+                "experimental": true
+            },
+            {
+                "name": "navigationPreloadFailed",
+                "description": "Fired when navigation preload request has failed.",
+                "parameters": [
+                    { "name": "requestId", "$ref": "RequestId", "description": "Request identifier." },
+                    { "name": "timestamp", "$ref": "Timestamp", "description": "Timestamp." },
+                    { "name": "errorMessage", "type": "string", "description": "Error message." }
+                ],
+                "experimental": true
+            },
+            {
+                "name": "navigationPreloadFinished",
+                "description": "Fired when navigation preload request has finished loading.",
+                "parameters": [
+                    { "name": "requestId", "$ref": "RequestId", "description": "Request identifier." },
+                    { "name": "timestamp", "$ref": "Timestamp", "description": "Timestamp." }
+                ],
+                "experimental": true
             }
         ]
     },
     {
         "domain": "Database",
         "experimental": true,
         "types": [
             {
                 "id": "DatabaseId",
                 "type": "string",
@@ skipping 2998 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." }
                 ]
             }
         ]
     }]
 }