[Smart Lock] Expose the easy_unlock.proximity_required pref via the chrome.preferencesPrivate API.

chrome/common/extensions/api/_permission_features.json

Index: chrome/common/extensions/api/_permission_features.json
diff --git a/chrome/common/extensions/api/_permission_features.json b/chrome/common/extensions/api/_permission_features.json
index 8e109cff9349e2142a9031eb539cf79a66ec1d96..9a6851d4f0729aefe3680b4d35870ab2824f7e12 100644
--- a/chrome/common/extensions/api/_permission_features.json
+++ b/chrome/common/extensions/api/_permission_features.json
@@ -819,19 +819,26 @@
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app"]
   },
-  "preferencesPrivate": {
-    "channel": "stable",
-    "extension_types": [
-      "extension"
-    ],
-    "whitelist": [
-      "C41AD9DCD670210295614257EF8C9945AD68D86E",  // Google Now
-      "D5736E4B5CF695CB93A2FB57E4FDC6E5AFAB6FE2",  // http://crbug.com/312900
-      "D57DE394F36DC1C3220E7604C575D29C51A6C495",  // http://crbug.com/319444
-      "3F65507A3B39259B38C8173C6FFA3D12DF64CCE9",  // http://crbug.com/371562
-      "852290F2442EEE45EF673B8DA6090112079012A2"   // http://crbug.com/375484
-    ]
-  },
+  "preferencesPrivate": [
+    {
+      "channel": "stable",
+      "extension_types": [
+        "extension"
+      ],
+      "whitelist": [
+        "C41AD9DCD670210295614257EF8C9945AD68D86E",  // Google Now
+        "D5736E4B5CF695CB93A2FB57E4FDC6E5AFAB6FE2",  // http://crbug.com/312900
+        "D57DE394F36DC1C3220E7604C575D29C51A6C495",  // http://crbug.com/319444
+        "3F65507A3B39259B38C8173C6FFA3D12DF64CCE9",  // http://crbug.com/371562
+        "852290F2442EEE45EF673B8DA6090112079012A2"   // http://crbug.com/375484
+      ]
+    },
+    {
+      "channel": "stable",
+      "extension_types": ["platform_app"],
+      "location": "component"
+    }
+  ],
   "principalsPrivate": {
     "channel": "stable",
     "extension_types": ["extension"],