From a2961d74e77e702d5ab1ba1199352f9db9570e83 Mon Sep 17 00:00:00 2001
From: Olli Pettay <Olli.Pettay@helsinki.fi>
Date: Mon, 6 Apr 2020 18:21:59 +0000
Subject: [PATCH] Bug 1625789, optimize CustomElement constructors out from
 cycle collection graph, r=mccr8

Using the method name GetExistingCustomElements() to match CustomElements(), even though
they both return CustomElementRegistry.

Differential Revision: https://phabricator.services.mozilla.com/D69853

--HG--
extra : moz-landing-system : lando
---
 dom/base/CustomElementRegistry.cpp   | 9 +++++++++
 dom/base/CustomElementRegistry.h     | 2 ++
 dom/base/nsCCUncollectableMarker.cpp | 5 +++++
 dom/base/nsGlobalWindowInner.cpp     | 4 ++++
 dom/base/nsGlobalWindowInner.h       | 1 +
 5 files changed, 21 insertions(+)

diff --git a/dom/base/CustomElementRegistry.cpp b/dom/base/CustomElementRegistry.cpp
index b03154ede0be..066b7b8ebe40 100644
--- a/dom/base/CustomElementRegistry.cpp
+++ b/dom/base/CustomElementRegistry.cpp
@@ -1244,6 +1244,15 @@ already_AddRefed<nsISupports> CustomElementRegistry::CallGetCustomInterface(
   return wrapper.forget();
 }
 
+void CustomElementRegistry::TraceDefinitions(JSTracer* aTrc) {
+  for (auto iter = mCustomDefinitions.Iter(); !iter.Done(); iter.Next()) {
+    RefPtr<CustomElementDefinition>& definition = iter.Data();
+    if (definition && definition->mConstructor) {
+      mozilla::TraceScriptHolder(definition->mConstructor, aTrc);
+    }
+  }
+}
+
 //-----------------------------------------------------
 // CustomElementReactionsStack
 
diff --git a/dom/base/CustomElementRegistry.h b/dom/base/CustomElementRegistry.h
index cce28249b879..fd300feffa90 100644
--- a/dom/base/CustomElementRegistry.h
+++ b/dom/base/CustomElementRegistry.h
@@ -466,6 +466,8 @@ class CustomElementRegistry final : public nsISupports, public nsWrapperCache {
     elements->PutEntry(elem);
   }
 
+  void TraceDefinitions(JSTracer* aTrc);
+
  private:
   ~CustomElementRegistry();
 
diff --git a/dom/base/nsCCUncollectableMarker.cpp b/dom/base/nsCCUncollectableMarker.cpp
index 076f4179abce..cd142977bccb 100644
--- a/dom/base/nsCCUncollectableMarker.cpp
+++ b/dom/base/nsCCUncollectableMarker.cpp
@@ -31,6 +31,7 @@
 #include "mozilla/dom/ChromeMessageBroadcaster.h"
 #include "mozilla/dom/ContentFrameMessageManager.h"
 #include "mozilla/dom/ContentProcessMessageManager.h"
+#include "mozilla/dom/CustomElementRegistry.h"
 #include "mozilla/dom/Element.h"
 #include "mozilla/dom/ParentProcessMessageManager.h"
 #include "mozilla/dom/BrowserChild.h"
@@ -467,6 +468,10 @@ void mozilla::dom::TraceBlackJS(JSTracer* aTrc, bool aIsShutdownGC) {
             if (elm) {
               elm->TraceListeners(aTrc);
             }
+            CustomElementRegistry* cer = inner->GetExistingCustomElements();
+            if (cer) {
+              cer->TraceDefinitions(aTrc);
+            }
           }
         }
 
diff --git a/dom/base/nsGlobalWindowInner.cpp b/dom/base/nsGlobalWindowInner.cpp
index 4b1d2a30034b..496f249f78be 100644
--- a/dom/base/nsGlobalWindowInner.cpp
+++ b/dom/base/nsGlobalWindowInner.cpp
@@ -2163,6 +2163,10 @@ CustomElementRegistry* nsGlobalWindowInner::CustomElements() {
   return mCustomElements;
 }
 
+CustomElementRegistry* nsGlobalWindowInner::GetExistingCustomElements() {
+  return mCustomElements;
+}
+
 Performance* nsPIDOMWindowInner::GetPerformance() {
   CreatePerformanceObjectIfNeeded();
   return mPerformance;
diff --git a/dom/base/nsGlobalWindowInner.h b/dom/base/nsGlobalWindowInner.h
index 6167d8b5e2b5..81e7fa1124f0 100644
--- a/dom/base/nsGlobalWindowInner.h
+++ b/dom/base/nsGlobalWindowInner.h
@@ -587,6 +587,7 @@ class nsGlobalWindowInner final : public mozilla::dom::EventTarget,
   mozilla::dom::Location* Location() override;
   nsHistory* GetHistory(mozilla::ErrorResult& aError);
   mozilla::dom::CustomElementRegistry* CustomElements() override;
+  mozilla::dom::CustomElementRegistry* GetExistingCustomElements();
   mozilla::dom::BarProp* GetLocationbar(mozilla::ErrorResult& aError);
   mozilla::dom::BarProp* GetMenubar(mozilla::ErrorResult& aError);
   mozilla::dom::BarProp* GetPersonalbar(mozilla::ErrorResult& aError);