Require confirmation for writable directory access.

chrome/common/extensions/api/_permission_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.
 
 {
   "activeTab": {
     "channel": "stable",
@@ skipping 259 matching lines @@
     "extension_types": ["platform_app"]
   }],
   "fileSystem.write": [{
     "channel": "stable",
     "extension_types": ["platform_app"]
   },{
     "channel": "stable",
     "extension_types": ["extension"],
     "whitelist": [ "2FC374607C2DF285634B67C64A2E356C607091C3" ]
   }],
+  "fileSystem.writeDirectory": [{
+    "channel": "trunk",
+    "extension_types": ["platform_app"]
+  }],

[not at google - send to devlin, 2013/09/03 17:07:04]

For the record: [{...}] in these files is equivalent to just {...} so you can
leave out the []s here and for fileSystem.directory.

In any case: for specifying these for-warning-only permissions you don't
currently need an entry in this file. See
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/common/exte...
for example. 

However, when http://crbug.com/280286 is partially in effect, you will.

However #2, I will try and get the arbitrary-install-prompt logic working, and
if so you won't.

So for now I'd suggest you just remove this.

[Sam McNally, 2013/09/04 00:21:30]

Having fileSystem with the [] and a child permission without the [] CHECK fails
at
https://code.google.com/p/chromium/codesearch/#chromium/src/chrome/common/ext....
Done.

[not at google - send to devlin, 2013/09/04 00:23:07]

Oh. I didn't even realised that those complex permissions worked with the child
permission logic.

   "fontSettings": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app"]
   },
   "fullscreen": {
     "channel": "stable",
     "extension_types": ["platform_app"]
   },
   "geolocation": {
     "channel": "stable",
@@ skipping 396 matching lines @@
   },
   "webRequestBlocking": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app"]
   },
   "webview": {
     "channel": "stable",
     "extension_types": ["platform_app"]
   }
 }