Use ParentFrameTaskRunners in WorkerLoaderProxyProvider::postTaskToLoader impls

third_party/WebKit/Source/core/dom/ExecutionContextTask.h

Index: third_party/WebKit/Source/core/dom/ExecutionContextTask.h
diff --git a/third_party/WebKit/Source/core/dom/ExecutionContextTask.h b/third_party/WebKit/Source/core/dom/ExecutionContextTask.h
index 8712967a38ad5bd98bb2acc2facaac4c8a746c7d..8f76cb9de2e59311aaf592971d4ee84a10272d91 100644
--- a/third_party/WebKit/Source/core/dom/ExecutionContextTask.h
+++ b/third_party/WebKit/Source/core/dom/ExecutionContextTask.h
@@ -48,6 +48,11 @@ class CORE_EXPORT ExecutionContextTask {
   ExecutionContextTask() {}
   virtual ~ExecutionContextTask() {}
   virtual void performTask(ExecutionContext*) = 0;
+
+  void performTaskIfContextIsValid(ExecutionContext* context) {
+    if (context)
+      performTask(context);
+  }
 };
 
 namespace internal {