Reland "Whitelist Imprivata extensions for networking.onc API"

This is a reland of 88854e15

Original change's description:
> Whitelist Imprivata extensions for networking.onc API
> 
> Whitelisting the Imprivata extensions so that they can send their local
> IP + MAC address to the Imprivata server, which are being used in the
> Imprivata admin consoleto assign the device to a specific "site" and
> also to assign computer policies to specific devices.
> 
> Bug: 1075877
> Change-Id: Id3a14b2ac5618dfcbc6c476da555153792debe57
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2169888
> Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
> Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
> Auto-Submit: Alexander Hendrich <hendrich@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#768029}

Bug: 1075877
Change-Id: I73fcce371de0568ea470ca518b856b8e52ba1914
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2203376
Auto-Submit: Alexander Hendrich <hendrich@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
Commit-Queue: Alexander Hendrich <hendrich@chromium.org>
Cr-Commit-Position: refs/heads/master@{#769060}

extensions/common/api/_permission_features.json

@@ -477,7 +477,12 @@
     "session_types": ["kiosk.autolaunched"]
   }, {
     "channel": "stable",
-    "extension_types": ["extension", "legacy_packaged_app", "platform_app"],
+    "extension_types": [
+      "extension",
+      "legacy_packaged_app",
+      "platform_app",
+      "login_screen_extension"
+    ],
     "platforms": ["chromeos", "mac", "win", "linux"],
     "whitelist": [
       "0DE0F05680A4A056BCEC864ED8DDA84296F82B40",  // http://crbug.com/434651
@@ -503,7 +508,15 @@
       "61FF4757F9420B62B19BA5C96084649339DB31F5",  // http://crbug.com/731941
       "6FB7E1B6C0247B687AC14772E87A117F5F5E4497",  // http://crbug.com/731941
       "9834387FDA1F66A1B5CA06CB442137B556F12F2A",  // http://crbug.com/772346
-      "A9A9FC0228ADF541F0334F22BEFB8F9C245B21D7"   // http://crbug.com/839189
+      "A9A9FC0228ADF541F0334F22BEFB8F9C245B21D7",  // http://crbug.com/839189
+      // TODO(crbug.com/1075877, hendrich) remove this when
+      // enterprise.networkingAttributes has landed
+      "E219EE36A3B40612FD2A8CD6937B03EF0C97D3FE", // Imprivata (login screen) crbug.com/1075877
+      "4DBFC1C52D6660DD90791976DF7FEF7B3D360509", // Imprivata (login screen) crbug.com/1075877
+      "CDA6A10BE50CE65C59B766D0CE6A27E8E0A1533F", // Imprivata (login screen) crbug.com/1075877
+      "A24DE1B21A67E25FB62AC8491642038FE25DA75B", // Imprivata (in-session) crbug.com/1075877
+      "6B25164FFE2BADB5F1DBBD301CC022170267022D", // Imprivata (in-session) crbug.com/1075877
+      "4D15F9AFCF54E56F0A6E06D22DD15F133DCF0882"  // Imprivata (in-session) crbug.com/1075877
     ]
   }],
   "networkingPrivate": {