Verify that a document is attached before firing an event.

third_party/WebKit/Source/core/frame/csp/ContentSecurityPolicy.cpp

Index: third_party/WebKit/Source/core/frame/csp/ContentSecurityPolicy.cpp
diff --git a/third_party/WebKit/Source/core/frame/csp/ContentSecurityPolicy.cpp b/third_party/WebKit/Source/core/frame/csp/ContentSecurityPolicy.cpp
index 94367f965e8f7bd2276f44c57496b08011ce3316..2bef27e76e580e7c90839ac791d3a713817daad5 100644
--- a/third_party/WebKit/Source/core/frame/csp/ContentSecurityPolicy.cpp
+++ b/third_party/WebKit/Source/core/frame/csp/ContentSecurityPolicy.cpp
@@ -1264,6 +1264,9 @@ void ContentSecurityPolicy::dispatchViolationEvents(
     const SecurityPolicyViolationEventInit& violationData,
     Element* element,
     Document* document) {
+  if (!document->domWindow())
+    return;
+
   SecurityPolicyViolationEvent* event = SecurityPolicyViolationEvent::create(
       EventTypeNames::securitypolicyviolation, violationData);
   DCHECK(event->bubbles());