Introduce a stable set of errors for inline install

chrome/browser/extensions/startup_helper.cc

Index: chrome/browser/extensions/startup_helper.cc
diff --git a/chrome/browser/extensions/startup_helper.cc b/chrome/browser/extensions/startup_helper.cc
index 4074b5f7c849ac6145256c68fb78777493b9e84e..7dd747f55add28e5d944e60bf4ed9ed6747223bd 100644
--- a/chrome/browser/extensions/startup_helper.cc
+++ b/chrome/browser/extensions/startup_helper.cc
@@ -213,7 +213,9 @@ class AppInstallHelper {
 
  private:
   WebstoreStandaloneInstaller::Callback Callback();
-  void OnAppInstallComplete(bool success, const std::string& error);
+  void OnAppInstallComplete(bool success,
+                            const std::string& error,
+                            webstore_install::Result result);
 
   DoneCallback done_callback_;
 
@@ -252,7 +254,8 @@ void AppInstallHelper::BeginInstall(
 }
 
 void AppInstallHelper::OnAppInstallComplete(bool success,
-                                            const std::string& error) {
+                                            const std::string& error,
+                                            webstore_install::Result result) {
   success_ = success;
   error_= error;
   done_callback_.Run();