PolyGerrit: Avatars did not make use of gerrit baseurl

Avatars did not work correctly on non-root "/" deployments.

Change-Id: I1272625c52b10e007685215fd664df0a7db17559

polygerrit-ui/app/elements/shared/gr-avatar/gr-avatar.html

@@ -14,6 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 -->
 
+<link rel="import" href="../../../behaviors/base-url-behavior/base-url-behavior.html">
 <link rel="import" href="../../../bower_components/polymer/polymer.html">
 <link rel="import" href="../gr-rest-api-interface/gr-rest-api-interface.html">
 

polygerrit-ui/app/elements/shared/gr-avatar/gr-avatar.js

@@ -28,6 +28,10 @@
       },
     },
 
+    behaviors: [
+      Gerrit.BaseUrlBehavior,
+    ],
+
     created: function() {
       this.hidden = true;
     },
@@ -64,7 +68,8 @@
           return avatars[i].url;
         }
       }
-      return '/accounts/' + account._account_id + '/avatar?s=' + this.imageSize;
+      return this.getBaseUrl() + '/accounts/' + account._account_id +
+          '/avatar?s=' + this.imageSize;
     },
   });
 })();