Fix crash on WebAPK startup

chrome/browser/android/webapk/webapk_installer.cc

Index: chrome/browser/android/webapk/webapk_installer.cc
diff --git a/chrome/browser/android/webapk/webapk_installer.cc b/chrome/browser/android/webapk/webapk_installer.cc
index 403297873b469a9e96ed2854038716e31e891f71..82c0c4776a1323df8d5ffcbe129e96209886a107 100644
--- a/chrome/browser/android/webapk/webapk_installer.cc
+++ b/chrome/browser/android/webapk/webapk_installer.cc
@@ -485,14 +485,11 @@ void WebApkInstaller::OnTimeout() {
 }
 
 void WebApkInstaller::OnSuccess() {
-  FinishCallback callback = finish_callback_;
-  std::string webapk_package = webapk_package_;
+  finish_callback_.Run(true, webapk_package_);
   delete this;
-  callback.Run(true, webapk_package);
 }
 
 void WebApkInstaller::OnFailure() {
-  FinishCallback callback = finish_callback_;
+  finish_callback_.Run(false, webapk_package_);
   delete this;
-  callback.Run(false, "");
 }