Begin to enable extension APIs in Extension Service Worker.

content/public/common/content_client.h

Index: content/public/common/content_client.h
diff --git a/content/public/common/content_client.h b/content/public/common/content_client.h
index dace907b95e7ae205d4c2cbae66da1721f5f672a..8e6805f2ef222bce1906b2f2edfabe617c651965 100644
--- a/content/public/common/content_client.h
+++ b/content/public/common/content_client.h
@@ -157,6 +157,10 @@ class CONTENT_EXPORT ContentClient {
   // trustworthy schemes should be added.
   virtual void AddServiceWorkerSchemes(std::set<std::string>* schemes) {}
 
+  // Returns whether or not V8 script extensions should be allowed for a
+  // service worker.
+  virtual bool AllowScriptExtensionForServiceWorker(const GURL& script_url);
+
   // Returns true if the embedder wishes to supplement the site isolation policy
   // used by the content layer. Returning true enables the infrastructure for
   // out-of-process iframes, and causes the content layer to consult