PassRefPtr is stolen by first agent invocation.

Source/core/inspector/InspectorInstrumentation.idl

Index: Source/core/inspector/InspectorInstrumentation.idl
diff --git a/Source/core/inspector/InspectorInstrumentation.idl b/Source/core/inspector/InspectorInstrumentation.idl
index d61434560df95f3503e03569e4c71bccb6aa7f5c..3abe82b17f7ff4a6e8a57b686dd45fcd097fde27 100644
--- a/Source/core/inspector/InspectorInstrumentation.idl
+++ b/Source/core/inspector/InspectorInstrumentation.idl
@@ -58,6 +58,9 @@
 *
 *   paramList: C++ parameter list with optional names. Names will be deduced from types if omitted but you have to
 *        specify explicit names for multiple parameters of the same type.
+*
+* Parameters with type PassRefPtr<T> are converted to raw pointers,
+* so reference will not be passed or released until all agents are notified.
 */
 
 interface InspectorInstrumentation {