Add chrome.power extension API.

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.
 
 {
   "activeTab": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app"],
     "min_manifest_version": 2
   },
@@ skipping 294 matching lines @@
     "extension_types": ["extension", "packaged_app"]
   },
   "pointerLock": {
     "channel": "dev",
     "extension_types": ["platform_app"]
   },
   "plugin": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app"]
   },
+  "power": {
+    "channel": "dev",
+    "platform": "chromeos",
+    "extension_types": ["extension", "hosted_app", "packaged_app"]

[not at google - send to devlin, 2013/03/19 21:16:39]

why hosted_app?

[Daniel Erat, 2013/03/19 23:39:38]

The intent is to permit e.g. a slide show app to prevent the screen from dimming
while displaying a presentation.

[not at google - send to devlin, 2013/03/20 00:25:50]

Ah, cool. Let's include platform_app too, then.

[Daniel Erat, 2013/03/20 03:45:25]

Whoops, I missed this.  I'll add it in a second change, if that's okay.

Is there documentation somewhere about what exactly platform_app refers to?  I
think I understand hosted vs. packaged, but I'm left guessing about "packaged"
-- does it refer to v1 apps?

[not at google - send to devlin, 2013/03/20 14:58:08]

Agreed, we need to document this. Packaged is v1, platform is v2.

+  },
   "privacy": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app"]
   },
   "proxy": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app"]
   },
   "pushMessaging": {
     "channel": "stable",
@@ skipping 150 matching lines @@
   },
   "webRequestBlocking": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app"]
   },
   "webview": {
     "channel": "stable",
     "extension_types": ["platform_app"]
   }
 }