Make sure to to check weak ptr validity before use in UnpackedInstaller

chrome/browser/extensions/unpacked_installer.cc

Index: chrome/browser/extensions/unpacked_installer.cc
diff --git a/chrome/browser/extensions/unpacked_installer.cc b/chrome/browser/extensions/unpacked_installer.cc
index 0f29e6c2fbb805cefaa8de399a4816bd0ab5f8a4..f37728ac3d4859cdca9b0d1cc8a6963056bd81c0 100644
--- a/chrome/browser/extensions/unpacked_installer.cc
+++ b/chrome/browser/extensions/unpacked_installer.cc
@@ -369,6 +369,9 @@ void UnpackedInstaller::ReportExtensionLoadError(const std::string &error) {
 void UnpackedInstaller::InstallExtension() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
+  if (!service_weak_.get())

[lazyboy, 2016/09/15 21:45:09]

Should we also Reset |callback_|?

[asargent_no_longer_on_chrome, 2016/09/16 00:03:24]

Good suggestion. Done. 

+    return;
+
   PermissionsUpdater perms_updater(service_weak_->profile());
   perms_updater.InitializePermissions(extension());
   perms_updater.GrantActivePermissions(extension());