drop http history if https if in histories

src/background/histories.js

@@ -1,9 +1,22 @@
+const filterHttp = (items) => {
+  const httpsHosts = items
+    .filter(item => item[1].protocol === 'https:')
+    .map(item => item[1].host);
+  const httpsHostSet = new Set(httpsHosts);
+  return items.filter(
+    item => !(item[1].protocol === 'http:' && httpsHostSet.has(item[1].host))
+  );
+};
+
 const getCompletions = (keyword) => {
   return browser.history.search({
     text: keyword,
     startTime: '1970-01-01'
   }).then((items) => {
-    return items.sort((x, y) => x.lastVisitTime < y.lastVisitTime).slice(0, 10);
+    return filterHttp(items.map(item => [item, new URL(item.url)]))
+      .sort((x, y) => x[0].lastVisitTime < y[0].lastVisitTime)
+      .slice(0, 10)
+      .map(item => item[0]);
   });
 };