[WIP] Worklet: Merge MainThreadWorklet and ThreadedWorklet into Worklet

third_party/WebKit/Source/core/workers/WorkletGlobalScopeProxy.h

Index: third_party/WebKit/Source/core/workers/WorkletGlobalScopeProxy.h
diff --git a/third_party/WebKit/Source/core/workers/WorkletGlobalScopeProxy.h b/third_party/WebKit/Source/core/workers/WorkletGlobalScopeProxy.h
index e651ddaafb7c8f9e278e8c39bf3e01ab35b45cf1..c981f313aa4969d1b9d5cdde81810b0cc59bc2a4 100644
--- a/third_party/WebKit/Source/core/workers/WorkletGlobalScopeProxy.h
+++ b/third_party/WebKit/Source/core/workers/WorkletGlobalScopeProxy.h
@@ -25,7 +25,7 @@ class CORE_EXPORT WorkletGlobalScopeProxy {
   // https://drafts.css-houdini.org/worklets/#fetch-and-invoke-a-worklet-script
   virtual void FetchAndInvokeScript(const KURL& module_url_record,
                                     WebURLRequest::FetchCredentialsMode,
-                                    WorkletPendingTasks*) {}
+                                    WorkletPendingTasks*) = 0;
 
   // Evaluates the given script source code. This should be called only for
   // threaded worklets that still use classic script loading.