Bug 832385 - Always NS_DROP_JS_OBJECTS in ~IDBWrapperCache. r=smaug,khuey a=tef+

content/base/public/nsContentUtils.h

@@ -2198,8 +2198,6 @@ private:
   static nsILineBreaker* sLineBreaker;
   static nsIWordBreaker* sWordBreaker;
 
-  static uint32_t sJSGCThingRootCount;
-
 #ifdef IBMBIDI
   static nsIBidiKeyboard* sBidiKeyboard;
 #endif

content/base/src/nsContentUtils.cpp

@@ -210,7 +210,6 @@ nsIContentPolicy *nsContentUtils::sContentPolicyService;
 bool nsContentUtils::sTriedToGetContentPolicy = false;
 nsILineBreaker *nsContentUtils::sLineBreaker;
 nsIWordBreaker *nsContentUtils::sWordBreaker;
-uint32_t nsContentUtils::sJSGCThingRootCount;
 #ifdef IBMBIDI
 nsIBidiKeyboard *nsContentUtils::sBidiKeyboard = nullptr;
 #endif
@@ -4574,28 +4573,18 @@ nsContentUtils::HoldJSObjects(void* aScriptObjectHolder,
 {
   NS_ENSURE_TRUE(sXPConnect, NS_ERROR_UNEXPECTED);
 
-  nsresult rv = sXPConnect->AddJSHolder(aScriptObjectHolder, aTracer);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  if (sJSGCThingRootCount++ == 0) {
-    nsLayoutStatics::AddRef();
-  }
-  NS_LOG_ADDREF(sXPConnect, sJSGCThingRootCount, "HoldJSObjects",
-                sizeof(void*));
-
-  return NS_OK;
+  return sXPConnect->AddJSHolder(aScriptObjectHolder, aTracer);
 }
 
 /* static */
 nsresult
 nsContentUtils::DropJSObjects(void* aScriptObjectHolder)
 {
-  NS_LOG_RELEASE(sXPConnect, sJSGCThingRootCount - 1, "HoldJSObjects");
-  nsresult rv = sXPConnect->RemoveJSHolder(aScriptObjectHolder);
-  if (--sJSGCThingRootCount == 0) {
-    nsLayoutStatics::Release();
+  if (!sXPConnect) {
+    return NS_OK;
   }
-  return rv;
+
+  return sXPConnect->RemoveJSHolder(aScriptObjectHolder);
 }
 
 #ifdef DEBUG

dom/indexedDB/IDBWrapperCache.cpp

@@ -40,9 +40,9 @@ NS_IMPL_RELEASE_INHERITED(IDBWrapperCache, nsDOMEventTargetHelper)
 
 IDBWrapperCache::~IDBWrapperCache()
 {
-  if (mScriptOwner) {
-    NS_DROP_JS_OBJECTS(this, IDBWrapperCache);
-  }
+  mScriptOwner = nullptr;
+  nsContentUtils::ReleaseWrapper(this, this);
+  NS_DROP_JS_OBJECTS(this, IDBWrapperCache);
 }
 
 bool

js/xpconnect/src/XPCJSRuntime.cpp

@@ -251,7 +251,11 @@ nsresult
 XPCJSRuntime::AddJSHolder(void* aHolder, nsScriptObjectTracer* aTracer)
 {
     MOZ_ASSERT(aTracer->Trace, "AddJSHolder needs a non-null Trace function");
+    bool wasEmpty = mJSHolders.Count() == 0;
     mJSHolders.Put(aHolder, aTracer);
+    if (wasEmpty && mJSHolders.Count() == 1) {
+        nsLayoutStatics::AddRef();
+    }
 
     return NS_OK;
 }
@@ -259,7 +263,11 @@ XPCJSRuntime::AddJSHolder(void* aHolder, nsScriptObjectTracer* aTracer)
 nsresult
 XPCJSRuntime::RemoveJSHolder(void* aHolder)
 {
+    bool hadOne = mJSHolders.Count() == 1;
     mJSHolders.Remove(aHolder);
+    if (hadOne && mJSHolders.Count() == 0) {
+        nsLayoutStatics::Release();
+    }
 
     return NS_OK;
 }