Introduce infrastructure for tracing ScriptWrappables.

third_party/WebKit/Source/bindings/core/v8/DOMWrapperWorld.cpp

Index: third_party/WebKit/Source/bindings/core/v8/DOMWrapperWorld.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/DOMWrapperWorld.cpp b/third_party/WebKit/Source/bindings/core/v8/DOMWrapperWorld.cpp
index 62ee227650a36c24720f7bb4e9295a1c5cb1f41d..57af6a761c850e679631cb5e46dde1b8b39434a5 100644
--- a/third_party/WebKit/Source/bindings/core/v8/DOMWrapperWorld.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/DOMWrapperWorld.cpp
@@ -137,6 +137,25 @@ void DOMWrapperWorld::allWorldsInMainThread(Vector<RefPtr<DOMWrapperWorld>>& wor
         worlds.append(it->value);
 }
 
+void DOMWrapperWorld::markWrappersInAllWorlds(ScriptWrappable* scriptWrappable, v8::Isolate* isolate)
+{
+    // TODO(hlopko): Currently wrapper in one world will keep wrappers in all
+    // worlds alive (possibly holding on entire documents). This is neither
+    // needed (there is no way to get from one wrapper to another), nor wanted
+    // (big performance and memory overhead).
+    ASSERT(isMainThread());

[haraken, 2016/04/19 04:58:30]

How is it guaranteed that this function is not called in worker threads?

[Marcel Hlopko, 2016/04/19 12:40:29]

I changed the assert to if (...) return.

+    // marking for the main world
+    scriptWrappable->markWrapper(isolate);
+    WorldMap& isolatedWorlds = isolatedWorldMap();
+    for (WorldMap::iterator it = isolatedWorlds.begin(); it != isolatedWorlds.end(); ++it) {
+        DOMDataStore& dataStore = it->value->domDataStore();

[haraken, 2016/04/19 04:58:30]

You can use:

  for (auto& isolatedWorld : isolatedWorlds.values())

[Marcel Hlopko, 2016/04/19 12:40:29]

Done.

+        if (dataStore.containsWrapper(scriptWrappable)) {
+            // marking for the isolated worlds
+            dataStore.markWrapper(scriptWrappable, isolate);
+        }
+    }
+}
+
 DOMWrapperWorld::~DOMWrapperWorld()
 {
     ASSERT(!isMainWorld());