Initialize download scheme preference

The download dialog checks the logged-in property to determine whether
it should check user preferences for a default download scheme.
Previously, however, it would check the flag before it had been
completely initialized (it starts out with a value of false) resulting
in the preferred scheme never being selected.

With this change, the download dialog reacts to changes in the logged-in
property instead of in the "attached" lifecycle method.

Bug: Issue 4203
But: Issue 5147
Change-Id: Ic412b1d9a04cc6083b090d7767172e541578e5c3

polygerrit-ui/app/elements/change/gr-download-dialog/gr-download-dialog.js

@@ -30,6 +30,7 @@
       loggedIn: {
         type: Boolean,
         value: false,
+        observer: '_loggedInChanged',
       },
 
       _schemes: {
@@ -49,15 +50,6 @@
       Gerrit.RESTClientBehavior,
     ],
 
-    attached: function() {
-      if (!this.loggedIn) { return; }
-      this.$.restAPI.getPreferences().then(function(prefs) {
-        if (prefs.download_scheme) {
-          this._selectedScheme = prefs.download_scheme;
-        }
-      }.bind(this));
-    },
-
     focus: function() {
       this.$.download.focus();
     },
@@ -70,6 +62,15 @@
       };
     },
 
+    _loggedInChanged: function(loggedIn) {
+      if (!loggedIn) { return; }
+      this.$.restAPI.getPreferences().then(function(prefs) {
+        if (prefs.download_scheme) {
+          this._selectedScheme = prefs.download_scheme;
+        }
+      }.bind(this));
+    },
+
     _computeDownloadCommands: function(change, patchNum, _selectedScheme) {
       var commandObj;
       for (var rev in change.revisions) {

polygerrit-ui/app/elements/change/gr-download-dialog/gr-download-dialog_test.html

@@ -162,6 +162,22 @@ limitations under the License.
         assert.isFalse(el.hasAttribute('selected'));
       });
     });
+
+    test('loads scheme from preferences w/o initial login', function(done) {
+      stub('gr-rest-api-interface', {
+        getPreferences: function() {
+          return Promise.resolve({download_scheme: 'repo'});
+        },
+      });
+
+      element.loggedIn = true;
+
+      assert.isTrue(element.$.restAPI.getPreferences.called);
+      element.$.restAPI.getPreferences.lastCall.returnValue.then(function() {
+        assert.equal(element._selectedScheme, 'repo');
+        done();
+      });
+    });
   });
 
   suite('gr-download-dialog tests', function() {