Use project lookup on change starring requests

Change-Id: Iee8de3c68b3f78222a4ef63ba5de680a17033674
(cherry picked from commit f91e636ffb)

polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.js

@@ -2086,11 +2086,18 @@
     },
 
     saveChangeStarred(changeNum, starred) {
+      // Some servers may require the project name to be provided
+      // alongside the change number, so resolve the project name
+      // first.
+      return this.getFromProjectLookup(changeNum).then(project => {
+        const url = '/accounts/self/starred.changes/' +
+            (project ? encodeURIComponent(project) + '~' : '') + changeNum;
         return this._send({
           method: starred ? 'PUT' : 'DELETE',
-        url: '/accounts/self/starred.changes/' + changeNum,
+          url,
           anonymizedUrl: '/accounts/self/starred.changes/*',
         });
+      });
     },
 
     saveChangeReviewed(changeNum, reviewed) {

polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface_test.html

@@ -1446,5 +1446,28 @@ limitations under the License.
       flushAsynchronousOperations();
       assert.isTrue(handler.calledOnce);
     });
+
+    test('saveChangeStarred', async () => {
+      sandbox.stub(element, 'getFromProjectLookup')
+          .returns(Promise.resolve('test'));
+      const sendStub =
+          sandbox.stub(element, '_send').returns(Promise.resolve());
+
+      await element.saveChangeStarred(123, true);
+      assert.isTrue(sendStub.calledOnce);
+      assert.deepEqual(sendStub.lastCall.args[0], {
+        method: 'PUT',
+        url: '/accounts/self/starred.changes/test~123',
+        anonymizedUrl: '/accounts/self/starred.changes/*',
+      });
+
+      await element.saveChangeStarred(456, false);
+      assert.isTrue(sendStub.calledTwice);
+      assert.deepEqual(sendStub.lastCall.args[0], {
+        method: 'DELETE',
+        url: '/accounts/self/starred.changes/test~456',
+        anonymizedUrl: '/accounts/self/starred.changes/*',
+      });
+    });
   });
 </script>