Add ServiceWorkerErrorMessage to ServiceWorker DevTool's protocol.

Source/devtools/protocol.json

 {
     "version": { "major": "1", "minor": "1" },
     "domains": [{
         "domain": "Inspector",
         "hidden": true,
         "types": [],
         "commands": [
             {
                 "name": "enable",
                 "description": "Enables inspector domain notifications."
@@ skipping 4071 matching lines @@
                 "description": "ServiceWorker registration.",
                 "properties": [
                     { "name": "registrationId", "type": "string" },
                     { "name": "scopeURL", "type": "string" },
                     { "name": "isDeleted", "type": "boolean", "optional": true }
                 ]
             },
             {
                 "id": "ServiceWorkerVersionRunningStatus",
                 "type": "string",
-                "hidden": true,
                 "enum": ["stopped", "starting", "running", "stopping"]
             },
             {
                 "id": "ServiceWorkerVersionStatus",
                 "type": "string",
-                "hidden": true,
                 "enum": ["new", "installing", "installed", "activating", "activated", "redundant"]
             },
             {
                 "id": "ServiceWorkerVersion",
                 "type": "object",
                 "description": "ServiceWorker version.",
                 "properties": [
                     { "name": "versionId", "type": "string" },
                     { "name": "registrationId", "type": "string" },
                     { "name": "scriptURL", "type": "string" },
                     { "name": "runningStatus", "$ref": "ServiceWorkerVersionRunningStatus" },
                     { "name": "status", "$ref": "ServiceWorkerVersionStatus" }
                 ]
+            },
+            {
+                "id": "ServiceWorkerErrorMessage",
+                "type": "object",
+                "description": "ServiceWorker error message.",
+                "properties": [
+                    { "name": "errorMessage", "type": "string" },
+                    { "name": "registrationId", "type": "string" },
+                    { "name": "versionId", "type": "string" },
+                    { "name": "sourceURL", "type": "string" },
+                    { "name": "lineNumber", "type": "integer" },
+                    { "name": "columnNumber", "type": "integer" }
+                ]
             }
         ],
         "commands": [
             {
                 "name": "enable",
                 "handlers": ["browser"]
             },
             {
                 "name": "disable",
                 "handlers": ["browser"]
@@ skipping 72 matching lines @@
                     { "name": "registrations", "type": "array", "items": { "$ref": "ServiceWorkerRegistration" } }
                 ],
                 "handlers": ["browser"]
             },
             {
                 "name": "workerVersionUpdated",
                 "parameters": [
                     { "name": "versions", "type": "array", "items": { "$ref": "ServiceWorkerVersion" } }
                 ],
                 "handlers": ["browser"]
+            },
+            {
+                "name": "workerErrorReported",
+                "parameters": [
+                    { "name": "errorMessage", "$ref": "ServiceWorkerErrorMessage" }
+                ],
+                "handlers": ["browser"]
             }
         ]
     },
     {
         "domain": "Canvas",
         "hidden": true,
         "types": [
             {
                 "id": "ResourceId",
                 "type": "string",
@@ skipping 852 matching lines @@
                 ],
                 "returns": [
                     { "name": "accessibilityNode", "$ref": "AXNode", "description": "The <code>Accessibility.AXNode</code> for this DOM node, if it exists.", "optional": true }
                 ],
                 "description": "Fetches the accessibility node for this DOM node, if it exists.",
                 "hidden": true
             }
         ]
     }]
 }