Bug 1647695 - Expose ChildID on frozen nsIHangReport;r=mconley

Differential Revision: https://phabricator.services.mozilla.com/D83665

dom/ipc/ProcessHangMonitor.cpp

@@ -1214,6 +1214,15 @@ HangMonitoredProcess::UserCanceled() {
   return NS_OK;
 }
 
+NS_IMETHODIMP
+HangMonitoredProcess::GetChildID(uint64_t* aChildID) {
+  if (!mContentParent) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+  *aChildID = mContentParent->ChildID();
+  return NS_OK;
+}
+
 static bool InterruptCallback(JSContext* cx) {
   if (HangMonitorChild* child = HangMonitorChild::Get()) {
     return child->InterruptCallback();

dom/ipc/nsIHangReport.idl

@@ -40,6 +40,9 @@ interface nsIHangReport : nsISupports
   // Only valid for PLUGIN_HANG reports.
   readonly attribute ACString pluginName;
 
+  // The child id of the process in which the hang happened.
+  readonly attribute unsigned long long childID;
+
   // Called by front end code when user ignores or cancels
   // the notification.
   void userCanceled();