Bug 931249 - Patch 8 - Provide direct getter to the fact that we are loading a worker instead of relying on cache name. r=khuey

--HG--
extra : rebase_source : ad85e2de17f562449f041fcb66a061a319da45f0

dom/workers/ScriptLoader.cpp

@@ -314,6 +314,7 @@ public:
     : mCacheName(aWorkerPrivate->ServiceWorkerCacheName())
   {
     MOZ_ASSERT(aWorkerPrivate->IsServiceWorker());
+    MOZ_ASSERT(aWorkerPrivate->LoadScriptAsPartOfLoadingServiceWorkerScript());
     AssertIsOnMainThread();
   }
 
@@ -645,7 +646,7 @@ private:
     }
 
     if (!mWorkerPrivate->IsServiceWorker() ||
-        mWorkerPrivate->ServiceWorkerCacheName().IsEmpty()) {
+        !mWorkerPrivate->LoadScriptAsPartOfLoadingServiceWorkerScript()) {
       for (uint32_t index = 0, len = mLoadInfos.Length(); index < len;
            ++index) {
         nsresult rv = LoadScript(index);

dom/workers/WorkerPrivate.h

@@ -487,10 +487,24 @@ public:
   {
     MOZ_ASSERT(IsServiceWorker());
     AssertIsOnMainThread();
-    return mLoadingWorkerScript ?
+    return mLoadInfo.mServiceWorkerCacheName;
-             mLoadInfo.mServiceWorkerCacheName : EmptyString();
   }
-  
+
+  // This is used to handle importScripts(). When the worker is first loaded
+  // and executed, it happens in a sync loop. At this point it sets
+  // mLoadingWorkerScript to true. importScripts() calls that occur during the
+  // execution run in nested sync loops and so this continues to return true,
+  // leading to these scripts being cached offline.
+  // mLoadingWorkerScript is set to false when the top level loop ends.
+  // importScripts() in function calls or event handlers are always fetched
+  // from the network.
+  bool
+  LoadScriptAsPartOfLoadingServiceWorkerScript()
+  {
+    MOZ_ASSERT(IsServiceWorker());
+    return mLoadingWorkerScript;
+  }
+
   void
   SetLoadingWorkerScript(bool aLoadingWorkerScript)
   {