Move permissions manifest key to //extensions

Permissions are parsed in //extensions. Moving the manifset key to the
//extensions _manifest_features.json file would prevent app_shell from
warning about an unknown "permissions" key (if app_shell warnings were
printed).

BUG=652006
R=rdevlin.cronin@chromium.org

Review-Url: https://codereview.chromium.org/2391763003
Cr-Commit-Position: refs/heads/master@{#422632}

chrome/common/extensions/api/_manifest_features.json

@@ -191,12 +191,6 @@
     "channel": "stable",
     "extension_types": ["extension"]
   },
-  "permissions": {
-    "channel": "stable",
-    "extension_types": [
-      "extension", "legacy_packaged_app", "hosted_app", "platform_app"
-    ]
-  },
   "platforms": {
     "channel": "stable",
     "extension_types": "all"

extensions/common/api/_manifest_features.json

@@ -281,6 +281,12 @@
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app"]
   },
+  "permissions": {
+    "channel": "stable",
+    "extension_types": [
+      "extension", "legacy_packaged_app", "hosted_app", "platform_app"
+    ]
+  },
   "sandbox": {
     "channel": "stable",
     "extension_types": [