[Extensions] Remove ExtensionFunction::SetError()

extensions/browser/extension_function.cc

Index: extensions/browser/extension_function.cc
diff --git a/extensions/browser/extension_function.cc b/extensions/browser/extension_function.cc
index d47493e814ff5dbe8000bea2ff868bc5a2ddc1eb..5995ad1a3f2cce29bb295fe64479fd96a01ca324 100644
--- a/extensions/browser/extension_function.cc
+++ b/extensions/browser/extension_function.cc
@@ -312,10 +312,6 @@ const std::string& ExtensionFunction::GetError() const {
   return error_;
 }
 
-void ExtensionFunction::SetError(const std::string& error) {
-  error_ = error;
-}
-
 bool ExtensionFunction::user_gesture() const {
   return user_gesture_ || UserGestureForTests::GetInstance()->HaveGesture();
 }