Convert to browser action and use optional permissions

manifest.json

@@ -4,7 +4,7 @@
   "version"         : "2.2",
   "description"     : "Markdown Viewer",
 
-  "page_action": {
+  "browser_action": {
     "default_icon": {
       "19" : "/images/icon19.png",
       "38" : "/images/icon38.png"
@@ -25,15 +25,6 @@
   "content_scripts": [
     {
       "matches": [
-        "*://*/*.markdown",
-        "*://*/*.mdown",
-        "*://*/*.mkdn",
-        "*://*/*.md",
-        "*://*/*.mkd",
-        "*://*/*.mdwn",
-        "*://*/*.mdtxt",
-        "*://*/*.mdtext",
-        "*://*/*.text",
         "file:///*/*.markdown",
         "file:///*/*.mdown",
         "file:///*/*.mkdn",
@@ -44,12 +35,6 @@
         "file:///*/*.mdtext",
         "file:///*/*.text"
       ],
-      "exclude_matches": [
-        "*://bitbucket.org/*",
-        "*://getcomposer.org/*",
-        "*://github.com/*",
-        "*://gitlab.com/*"
-      ],
       "css": [
         "/css/content.css",
         "/css/prism.css"
@@ -99,7 +84,11 @@
   "homepage_url": "https://chrome.google.com/webstore/detail/markdown-viewer/ckkdlimhmcjmikdlpkmbgfkaikojcbjk",
 
   "permissions": [
-    "tabs",
     "storage"
+  ],
+
+  "optional_permissions": [
+    "http://*/",
+    "https://*/"
   ]
 }