Also fix the Windows and Linux side of async openExternal

atom/common/platform_util_linux.cc

@@ -92,14 +92,7 @@ bool OpenExternal(const GURL& url, bool activate) {
 void OpenExternal(const GURL& url, bool activate,
                   const OpenExternalCallback& callback) {
   // TODO(gabriel): Implement async open if callback is specified
-  bool opened = OpenExternal(url, activate);
-  v8::Isolate* isolate = v8::Isolate::GetCurrent();
-  if (!opened) {
-    callback.Run(v8::Exception::Error(
-      v8::String::NewFromUtf8(isolate, "Failed to open")));
-  } else {
-    callback.Run(v8::Null(isolate));
-  }
+  callback.Run(OpenExternal(url, activate) ? "" : "Failed to open");
 }
 
 bool MoveItemToTrash(const base::FilePath& full_path) {

atom/common/platform_util_win.cc

@@ -319,14 +319,7 @@ bool OpenExternal(const base::string16& url, bool activate) {
 void OpenExternal(const base::string16& url, bool activate,
                   const OpenExternalCallback& callback) {
   // TODO(gabriel): Implement async open if callback is specified
-  bool opened = OpenExternal(url, activate);
-  v8::Isolate* isolate = v8::Isolate::GetCurrent();
-  if (!opened) {
-    callback.Run(v8::Exception::Error(
-      v8::String::NewFromUtf8(isolate, "Failed to open")));
-  } else {
-    callback.Run(v8::Null(isolate));
-  }
+  callback.Run(OpenExternal(url, activate) ? "" : "Failed to open");
 }
 
 bool MoveItemToTrash(const base::FilePath& path) {