bug 1328964 add CycleCollectedJSContext::GetAsWorkletJSContext() and use it in IsOnWorkletThread() r=smaug

MozReview-Commit-ID: BUujWXYho1G

--HG--
extra : rebase_source : 78bb6736f74bb59913bc9499fcfdf7b0baa7870d

dom/worklet/WorkletThread.cpp

@@ -170,6 +170,8 @@ public:
     nsCycleCollector_shutdown();
   }
 
+  WorkletJSContext* GetAsWorkletJSContext() override { return this; }
+
   CycleCollectedJSRuntime* CreateRuntime(JSContext* aCx) override
   {
     return new WorkletJSRuntime(aCx);
@@ -426,8 +428,8 @@ WorkletThread::GetWorkletLoadInfo() const
 /* static */ bool
 WorkletThread::IsOnWorkletThread()
 {
-  const char* threadName = PR_GetThreadName(PR_GetCurrentThread());
-  return threadName && !strcmp(threadName, "worklet");
+  CycleCollectedJSContext* ccjscx = CycleCollectedJSContext::Get();
+  return ccjscx && ccjscx->GetAsWorkletJSContext();
 }
 
 /* static */ void

xpcom/base/CycleCollectedJSContext.h

@@ -32,6 +32,7 @@ class CycleCollectedJSRuntime;
 
 namespace dom {
 class Exception;
+class WorkletJSContext;
 } // namespace dom
 
 // Contains various stats about the cycle collection.
@@ -130,6 +131,8 @@ public:
     FinalizeNow,
   };
 
+  virtual dom::WorkletJSContext* GetAsWorkletJSContext() { return nullptr; }
+
   CycleCollectedJSRuntime* Runtime() const
   {
     MOZ_ASSERT(mRuntime);