Converted to pageAction so only appears on YouTube.com

background.js

@@ -1,10 +1,28 @@
+//Only make extension icon visible on YouTube.com
+const youtubeBaseUrl = 'youtube.com'	//lowercase matters
+chrome.runtime.onInstalled.addListener(function() {
+	// Replace all rules ...
+	chrome.declarativeContent.onPageChanged.removeRules(undefined, () => {
+		// With a new rule ...
+		chrome.declarativeContent.onPageChanged.addRules([{
+			conditions: [
+				new chrome.declarativeContent.PageStateMatcher({
+					pageUrl: { hostContains: youtubeBaseUrl },
+				})
+			],
+			// And shows the extension's page action
+			actions: [ new chrome.declarativeContent.ShowPageAction() ]
+		}])
+	})
+})
+
 
-const MAGIC_URL_POSTFIX = '&list=ULcxqQ59vzyTk'
-const YOUTUBE_VIDEO_URL_START = 'https://www.youtube.com/watch?v='
+const MAGIC_URL_POSTFIX = '&list=ULcxqQ59vzyTk'		//thing to append to make it play chronlogically
+const YOUTUBE_VIDEO_URL_START = 'https://www.youtube.com/watch?v='	//a youtube url without the videoID
 const regexMatchVideoId = /youtube.com\/watch\?v=([^&\?]*)/		//regular expression matches youtube.com/watch?v=[VIDEO_ID]	& captures the video ID since the ID is either the end of the string or ends at a question mark or ampersand
 
 //Browser action instead of popup
-chrome.browserAction.onClicked.addListener(tab=>{
+chrome.pageAction.onClicked.addListener(tab=>{
 	appendToUrl()
 })
 
@@ -14,7 +32,7 @@ function appendToUrl(){
 		let oldURL = currentTab.url
 		let videoId = oldURL.match(regexMatchVideoId)[1]	//get video id
 		let newUrl = YOUTUBE_VIDEO_URL_START + videoId + MAGIC_URL_POSTFIX
-		chrome.tabs.update(currentTab.id, {url: newUrl})
+		chrome.tabs.update(currentTab.id, {url: newUrl})	//update tab/reloads page with new location
 	})
 }
 

manifest.json

@@ -3,21 +3,23 @@
 
 	"name": "YouTube Chronological Order",
 	"description": "Watch YouTube videos in chronological order from any channel",
-	"version": "0.3.0",
-	"version_name": "0.3.0", 
+	"version": "0.4.0",
+	"version_name": "0.4.0", 
 
-	"browser_action": {
+	"page_action": {
 		// "default_icon": "assets/icons/icon.png",
 		"default_title": "(Alt+P) Watch channel videos in chronological order"
 	},
 	"permissions": [
+		"declarativeContent", 
 		"activeTab",
 		"tabs"
 	], 
 	"background": {
 		"scripts": [
 			"background.js"
-		]
+		],
+		"persistent": false
 	},
 	"commands": {
 		"appendToUrl": {