Implement externally_connectable! Web pages can now communicate directly with

chrome/common/extensions/api/_api_features.json

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// See c/c/e/features/* to understand this file, in particular feature.h,
+// simple_feature.h, and base_feature_provider.h.
+
 {
   "app": {
     "channel": "stable",
     "extension_types": ["hosted_app", "extension", "packaged_app"],
     "contexts": [
       "blessed_extension", "unblessed_extension", "content_script", "web_page"
     ],
     "matches": [
       "http://*/*", "https://*/*", "chrome-extension://*/*", "file://*/*"
     ]
@@ skipping 49 matching lines @@
     "contexts": ["blessed_extension", "unblessed_extension", "content_script"]
   },
   "runtime": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app", "platform_app"],
     "contexts": ["blessed_extension"]
   },
   "runtime.connect": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app", "platform_app"],
-    "contexts": ["blessed_extension", "unblessed_extension", "content_script"]
+    "contexts": "all",
+    "matches": ["<all_urls>"]
   },
   "runtime.getManifest": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app", "platform_app"],
     "contexts": ["blessed_extension", "unblessed_extension", "content_script"]
   },
   "runtime.getURL": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app", "platform_app"],
     "contexts": ["blessed_extension", "unblessed_extension", "content_script"]
@@ skipping 24 matching lines @@
     "contexts": ["blessed_extension", "unblessed_extension", "content_script"]
   },
   "runtime.requestUpdateCheck": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app", "platform_app"],
     "contexts": ["blessed_extension", "unblessed_extension", "content_script"]
   },
   "runtime.sendMessage": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app", "platform_app"],
-    "contexts": ["blessed_extension", "unblessed_extension", "content_script"]
+    "contexts": "all",
+    "matches": ["<all_urls>"]
   },
   "runtime.setUninstallUrl": {
     "channel": "dev",
     "extension_types": ["extension", "packaged_app", "platform_app"],
     "contexts": ["blessed_extension", "unblessed_extension", "content_script"]
   },
   "webRequestInternal": {
     "internal": true,
     "channel": "stable",
     "contexts": ["blessed_extension", "unblessed_extension", "content_script"]
   },
   "webstore": {
     // Hosted apps can use the webstore API from within a blessed context.
     "channel": "stable",
     "extension_types": ["hosted_app"],
     "contexts": ["blessed_extension", "web_page"],
     // Any webpage can use the webstore API.
     "matches": ["http://*/*", "https://*/*"]
   }
 }