From c8e205f9e6c1cb23da3fe500732b31ec4ba6be8d Mon Sep 17 00:00:00 2001
From: Gerben <gerben@treora.com>
Date: Fri, 18 Oct 2019 23:22:29 +0530
Subject: [PATCH] Load content script only for audio files.

---
 app/manifest.json         |  8 ++------
 app/scripts/background.js | 21 +++++++++++++++++++++
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/app/manifest.json b/app/manifest.json
index 3db8ef3..dcef13b 100644
--- a/app/manifest.json
+++ b/app/manifest.json
@@ -8,12 +8,8 @@
       "scripts/background.js"
     ]
   },
-  "content_scripts": [{
-      "matches": ["<all_urls>"],
-      "js": ["scripts/contentscript.js"],
-      "run_at": "document_end"
-  }],
   "permissions": [
-    "activeTab"
+    "<all_urls>",
+    "webRequest"
   ]
 }
diff --git a/app/scripts/background.js b/app/scripts/background.js
index e69de29..d2071d4 100644
--- a/app/scripts/background.js
+++ b/app/scripts/background.js
@@ -0,0 +1,21 @@
+async function onHeadersReceived({ responseHeaders, url, tabId }) {
+	const isAudio = responseHeaders.some(header =>
+		header.name === 'Content-Type' && header.value.startsWith('audio/')
+	);
+
+	if (isAudio) {
+		browser.tabs.executeScript(tabId, {
+			runAt: 'document_end',
+			file: '/scripts/contentscript.js',
+		});
+	}
+}
+
+browser.webRequest.onHeadersReceived.addListener(
+	onHeadersReceived,
+	{
+		urls: ['<all_urls>'],
+		types: ['main_frame'],
+	},
+	['responseHeaders'],
+);