Bug 1244247 - Remove racey sScriptSettingsTLSInitialized. r=bzbarsky

Differential Revision: https://phabricator.services.mozilla.com/D49213

--HG--
extra : moz-landing-system : lando

dom/script/ScriptSettings.cpp

@@ -29,7 +29,6 @@ namespace mozilla {
 namespace dom {
 
 static MOZ_THREAD_LOCAL(ScriptSettingsStackEntry*) sScriptSettingsTLS;
-static bool sScriptSettingsTLSInitialized;
 
 class ScriptSettingsStack {
  public:
@@ -118,15 +117,12 @@ void InitScriptSettings() {
   }
 
   sScriptSettingsTLS.set(nullptr);
-  sScriptSettingsTLSInitialized = true;
 }
 
 void DestroyScriptSettings() {
   MOZ_ASSERT(sScriptSettingsTLS.get() == nullptr);
 }
 
-bool ScriptSettingsInitialized() { return sScriptSettingsTLSInitialized; }
-
 ScriptSettingsStackEntry::ScriptSettingsStackEntry(nsIGlobalObject* aGlobal,
                                                    Type aType)
     : mGlobalObject(aGlobal), mType(aType), mOlder(nullptr) {

dom/script/ScriptSettings.h

@@ -31,12 +31,11 @@ namespace dom {
 class Document;
 
 /*
- * System-wide setup/teardown routines. Init and Destroy should be invoked
- * once each, at startup and shutdown (respectively).
+ * Per thread setup/teardown routines. Init and Destroy should be invoked
+ * once each, at startup and shutdown of the script runtime (respectively).
  */
 void InitScriptSettings();
 void DestroyScriptSettings();
-bool ScriptSettingsInitialized();
 
 /*
  * Static helpers in ScriptSettings which track the number of listeners

ipc/glue/MessageChannel.cpp

@@ -8,6 +8,7 @@
 #include "mozilla/ipc/MessageChannel.h"
 
 #include "mozilla/Assertions.h"
+#include "mozilla/CycleCollectedJSContext.h"
 #include "mozilla/DebugOnly.h"
 #include "mozilla/dom/ScriptSettings.h"
 #include "mozilla/ipc/ProcessChild.h"
@@ -112,7 +113,6 @@ using namespace mozilla::ipc;
 using mozilla::MonitorAutoLock;
 using mozilla::MonitorAutoUnlock;
 using mozilla::dom::AutoNoJSAPI;
-using mozilla::dom::ScriptSettingsInitialized;
 
 #define IPC_ASSERT(_cond, ...)                                           \
   do {                                                                   \
@@ -2079,7 +2079,9 @@ void MessageChannel::DispatchMessage(Message&& aMsg) {
   RefPtr<ActorLifecycleProxy> listenerProxy = mListener->GetLifecycleProxy();
 
   Maybe<AutoNoJSAPI> nojsapi;
-  if (ScriptSettingsInitialized() && NS_IsMainThread()) nojsapi.emplace();
+  if (NS_IsMainThread() && CycleCollectedJSContext::Get()) {
+    nojsapi.emplace();
+  }
 
   nsAutoPtr<Message> reply;