Avoid sync IPCs for FileSystem API

chrome/renderer/worker_permission_client_proxy.cc

Index: chrome/renderer/worker_permission_client_proxy.cc
diff --git a/chrome/renderer/worker_permission_client_proxy.cc b/chrome/renderer/worker_permission_client_proxy.cc
index 7d8a65e87ea92419838ee79d97a2ed33ebdd0744..24c2707e6d31d4a6394d4230d9ebb8601bb5c57f 100644
--- a/chrome/renderer/worker_permission_client_proxy.cc
+++ b/chrome/renderer/worker_permission_client_proxy.cc
@@ -7,6 +7,7 @@
 #include "content/public/renderer/render_frame.h"
 #include "content/public/renderer/render_thread.h"
 #include "ipc/ipc_sync_message_filter.h"
+#include "third_party/WebKit/public/platform/WebPermissionCallbacks.h"
 #include "third_party/WebKit/public/web/WebDocument.h"
 #include "third_party/WebKit/public/web/WebFrame.h"
 #include "third_party/WebKit/public/web/WebSecurityOrigin.h"
@@ -51,6 +52,19 @@ bool WorkerPermissionClientProxy::allowFileSystem() {
   return result;
 }
 
+void WorkerPermissionClientProxy::requestFileSystemAccess(
+    const blink::WebPermissionCallbacks& callbacks) {
+  bool result = false;
+  sync_message_filter_->Send(new ChromeViewHostMsg_AllowFileSystem(
+      routing_id_, document_origin_url_, top_frame_origin_url_, &result));
+  blink::WebPermissionCallbacks permission_callbacks(callbacks);
+  if (result) {
+    permission_callbacks.doAllow();
+    return;
+  }
+  permission_callbacks.doDeny();
+}
+
 bool WorkerPermissionClientProxy::allowIndexedDB(
     const blink::WebString& name) {
   if (is_unique_origin_)