Align with Ember's HistoryLocation router

addon/locations/router-scroll.js

@@ -1,24 +1,29 @@
 import Ember from 'ember';
 
+function _uuid() {
+  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
+    var r, v;
+    r = Math.random() * 16 | 0;
+    v = c === 'x' ? r : r & 3 | 8;
+    return v.toString(16);
+  });
+}
+
 const {
   get,
   HistoryLocation,
 } = Ember;
 
 export default HistoryLocation.extend({
-  init(...args) {
-    this._super(...args);
-    this.stateCounter = 0;
-  },
   pushState(path) {
-    const id = `${this.stateCounter++}`;
-    const state = { path, id };
+    const uuid = _uuid();
+    const state = { path, uuid };
     get(this, 'history').pushState(state, null, path);
     this._previousURL = this.getURL(); // eslint-disable-line no-underscore-dangle
   },
   replaceState(path) {
-    const id = `${this.stateCounter++}`;
-    const state = { path, id };
+    const uuid = _uuid();
+    const state = { path, uuid };
     get(this, 'history').replaceState(state, null, path);
     this._previousURL = this.getURL(); // eslint-disable-line no-underscore-dangle
   },

addon/services/router-scroll.js

@@ -26,11 +26,11 @@ export default Service.extend({
   },
 
   position: computed(function position() {
-    const scrollMap = get(this, 'scrollMap');
-    const stateId = get(window, 'history.state.id');
+    let scrollMap = get(this, 'scrollMap');
+    let stateUuid = get(window, 'history.state.uuid');
 
-    set(this, 'key', stateId);
-    const key = get(this, 'key') || '-1';
+    set(this, 'key', stateUuid);
+    let key = getWithDefault(this, 'key', '-1');
 
     return getWithDefault(scrollMap, key, { x: 0, y: 0 });
   }).volatile(),

tests/unit/services/router-scroll-test.js

@@ -34,10 +34,10 @@ test('updating will not set `scrollMap` to the current scroll position if `key`
   assert.deepEqual(get(service, 'scrollMap'), { });
 });
 
-test('computing the position for an existing state id return the coords', function(assert) {
+test('computing the position for an existing state uuid return the coords', function(assert) {
   let service = this.subject();
   let state = window.history.state;
-  window.history.replaceState({id: '123'}, null);
+  window.history.replaceState({uuid: '123'}, null);
 
   let expected = { x: 1, y: 1 };
   set(service, 'scrollMap.123', expected);
@@ -48,7 +48,7 @@ test('computing the position for an existing state id return the coords', functi
 test('computing the position for a state without a cached scroll position returns default', function(assert) {
   let service = this.subject();
   let state = window.history.state;
-  window.history.replaceState({id: '123'}, null);
+  window.history.replaceState({uuid: '123'}, null);
 
   let expected = { x: 0, y: 0 };
   assert.deepEqual(get(service, 'position'), expected);