[MD Extensions] Include the manifest code snippet in load errors

chrome/browser/resources/md_extensions/service.js

Index: chrome/browser/resources/md_extensions/service.js
diff --git a/chrome/browser/resources/md_extensions/service.js b/chrome/browser/resources/md_extensions/service.js
index c3f9d5272ca8b97bfd8a82ae4e2d984130316fe8..97054bd803ee12a7f6399654e9c656068a1d488b 100644
--- a/chrome/browser/resources/md_extensions/service.js
+++ b/chrome/browser/resources/md_extensions/service.js
@@ -253,8 +253,16 @@ cr.define('extensions', function() {
 
     /** @override */
     loadUnpacked: function() {
-      chrome.developerPrivate.loadUnpacked({failQuietly: true}, () => {
-        // TODO(devlin): Show the load error dialog if something went wrong.
+      chrome.developerPrivate.loadUnpacked(
+          {failQuietly: true, populateError: true}, (loadError) => {

[michaelpg, 2017/03/24 02:59:02]

nit: start the lambda on its own line, so it stands out as a function and passes
the Rectangle Rule.

[Devlin, 2017/03/24 16:03:08]

Done.

+        if (chrome.runtime.lastError) {
+          // The lastError here is just that the user closed the dialog.

[michaelpg, 2017/03/24 02:59:02]

assert(lastError matches what you expect) in addition to (or instead of) comment

[Devlin, 2017/03/24 16:03:08]

Done.

+          return;
+        }
+        if (loadError) {
+          this.manager_.loadError.set('loadError', loadError);
+          this.manager_.loadError.show();
+        }
       });
     },