Video Player: Use external entries instead of isolated entries

ui/file_manager/video_player/manifest.json

 {
   // chrome-extension://jcgeabjmjgoblfofpppfkcoakmfobdko/
   "key": "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAw0/gRbJc545iEGRZs20Rl/HtrSUp8H3gJd4Y6hCe0CG1xQiJhZ5nc8qZyxa96gMxRAKBq54S6sjVVtV6uS70oU6FvrvwItByYkkqr4ZE7eMJKwMqnGItxWbh6KBodf89lpKoIy6MtYTqubBhXB/IQBZsXah90tXwRzaaJNWw+2BBRIhcPsH3ng+wgN7rwFxo4HIv9ZpqkYlx90rwkfjOmKPPnSXyXFIBJfmqfdbd8PLtcxzzOTE+vxwoXZuYWrthKm4uKfNqXIYns74sSJlqyKfctuR+nQdNh8uePv0e+/Ul3wER1/jIXULLjfyoaklyDs+ak3SDf+xWScJ+0LJ0AwIDAQAB",
   "manifest_version": 2,
   "name": "Video Player",
   "version": "1.0",
   "description": "Video Player",
   "display_in_launcher": false,
   "incognito" : "split",
   "icons": {
@@ skipping 30 matching lines @@
         "ogm",
         "ogv",
         "ogx",
         "webm"
       ]
     }
   },
   "app": {
     "background": {
       "scripts": [
-        "js/error_util.js",
-        "js/test_util.js",
-        "js/background.js",
         "chrome://resources/js/cr.js",
         "chrome://resources/js/cr/event_target.js",
         "chrome://resources/js/cr/ui/array_data_model.js",
         "chrome://resources/js/load_time_data.js",
         "chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj/common/js/util.js",
         "chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj/common/js/async_util.js",
         "chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj/common/js/volume_manager_common.js",
         "chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj/background/js/volume_manager.js",
-        "chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj/foreground/js/file_type.js"
+        "chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj/foreground/js/file_type.js",
+        "js/error_util.js",
+        "js/test_util.js",
+        // The main background script must be at the end.
+        "js/background.js"
       ]
     },
     // The following ids are cast extension's ids .
     // - boadgeojelhgndaghljhdicfkmllpafd (release)
     // - dliochdbjfkdbacpmhlcpmleaejidimm (beta)
     // - hfaagokkkhdbgiakmmlclaapfelnkoah
     // - fmfcbgogabcbclcofgocippekhfcmgfj
     // - enhhojjnijigcajfphajepfemndkmdlo
     "content_security_policy": "default-src 'none'; script-src 'self' chrome://resources chrome-extension://boadgeojelhgndaghljhdicfkmllpafd chrome-extension://dliochdbjfkdbacpmhlcpmleaejidimm chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj chrome-extension://fmfcbgogabcbclcofgocippekhfcmgfj chrome-extension://enhhojjnijigcajfphajepfemndkmdlo; style-src 'self' chrome://resources 'unsafe-inline'; img-src 'self' chrome://theme chrome://resources data:; media-src 'self'; object-src 'self'"
   }
 }