scrollToBottom option

scripts/background/actions.js

@@ -136,6 +136,19 @@ function queryUrl(tab, expected, log) {
     return sendMessage(tab, req, log, cond);
 }
 
+/**
+ * get the url of the target tab
+ * @param {any} tab target tab
+ * @param {string} expected if specified, queryUrl resolves only when tab url equals to expected
+ * @returns {Promise<string>} a promise of the url
+ */
+function scrollToBottom(tab) {
+    let req = {
+        action: ACTION_SCROLL_BOTTOM
+    }
+    return sendMessage(tab, req, 'Scroll to page bottom...');
+}
+
 async function createTab(url, active) {
     return new Promise((resolve, reject) => {
         chrome.tabs.create({