Add the ability to return descedant event listeners.

third_party/WebKit/Source/core/inspector/ThreadDebugger.cpp

Index: third_party/WebKit/Source/core/inspector/ThreadDebugger.cpp
diff --git a/third_party/WebKit/Source/core/inspector/ThreadDebugger.cpp b/third_party/WebKit/Source/core/inspector/ThreadDebugger.cpp
index 5feed2b53378580d95ed3c82e61b9a35f98fa700..393f7436ef191ac04f44aec4ace5d637a015dd68 100644
--- a/third_party/WebKit/Source/core/inspector/ThreadDebugger.cpp
+++ b/third_party/WebKit/Source/core/inspector/ThreadDebugger.cpp
@@ -298,10 +298,26 @@ void ThreadDebugger::getEventListenersCallback(const v8::FunctionCallbackInfo<v8
     v8::Isolate* isolate = info.GetIsolate();
     v8::Local<v8::Context> context = isolate->GetCurrentContext();
 
+    EventListenerFilter filterMask = static_cast<EventListenerFilter>(EventListenerFilter::ShowPassive | EventListenerFilter::ShowBlocking);
+    if (info.Length() > 1 && info[1]->IsObject()) {
+        v8::Local<v8::Object> options = v8::Local<v8::Object>::Cast(info[1]);
+
+        v8::Local<v8::Value> setting;
+        if (options->Get(context, v8String(isolate, "descendants")).ToLocal(&setting) && setting->IsTrue())
+            filterMask = static_cast<EventListenerFilter>(filterMask | EventListenerFilter::ShowDescendants);
+
+        if (options->Get(context, v8String(isolate, "passive")).ToLocal(&setting) && !setting->IsUndefined()) {
+            if (setting->IsFalse())
+                filterMask = static_cast<EventListenerFilter>(filterMask & ~EventListenerFilter::ShowPassive);
+            else
+                filterMask = static_cast<EventListenerFilter>(filterMask & ~EventListenerFilter::ShowBlocking);
+        }
+    }
+
     V8EventListenerInfoList listenerInfo;
     // eventListeners call can produce message on ErrorEvent during lazy event listener compilation.
     debugger->muteWarningsAndDeprecations();
-    InspectorDOMDebuggerAgent::eventListenersInfoForTarget(isolate, info[0], listenerInfo);
+    InspectorDOMDebuggerAgent::eventListenersInfoForTarget(isolate, info[0], filterMask, listenerInfo);
     debugger->unmuteWarningsAndDeprecations();
 
     v8::Local<v8::Object> result = v8::Object::New(isolate);
@@ -315,11 +331,20 @@ void ThreadDebugger::getEventListenersCallback(const v8::FunctionCallbackInfo<v8
     v8::Local<v8::Array> listeners;
     size_t outputIndex = 0;
     for (auto& info : listenerInfo) {
+        // Skip contexts not associated with the current context.
+        if (info.handler->CreationContext() != context)

[caseq, 2016/05/31 21:36:49]

I think this is the right places for this check to be, but my understanding is
that Pavel's suggestion was to use some security-origin based check (e.g.
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...).
Unlike simple checking for context, this should allow access to same-origin
subframes, though we also need to assure these will work well for
extension-based listeners (which we don't want to expose).

+            continue;
         if (currentEventType != info.eventType) {
             currentEventType = info.eventType;
-            listeners = v8::Array::New(isolate);
-            outputIndex = 0;
-            result->Set(v8String(isolate, currentEventType), listeners);
+            v8::Local<v8::Value> matchingList;
+            if (result->Get(context, v8String(isolate, currentEventType)).ToLocal(&matchingList) && matchingList->IsArray()) {
+                listeners = v8::Local<v8::Array>::Cast(matchingList);
+                outputIndex = listeners->Length();
+            } else {
+                listeners = v8::Array::New(isolate);
+                outputIndex = 0;
+                result->Set(v8String(isolate, currentEventType), listeners);
+            }
         }
 
         v8::Local<v8::Object> listenerObject = v8::Object::New(isolate);