Whitelist PDF Viewer to use metricsPrivate

Bug: 768982
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I030f371dcbc1fbef3bcc01ce1daa110cd5b6ad1f
Reviewed-on: https://chromium-review.googlesource.com/807144Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521845}

chrome/browser/resources/pdf/manifest.json

@@ -9,6 +9,7 @@
   "incognito": "split",
   "permissions": [
     "<all_urls>",
+    "metricsPrivate",
     "resourcesPrivate"
   ],
   "mime_types": [

extensions/common/api/_permission_features.json

@@ -397,7 +397,8 @@
       "2B6C6A4A5940017146F3E58B7F90116206E84685",  // http://crbug.com/642141
       "B6C2EFAB3EC3BF6EF03701408B6B09A67B2D0069",  // http://crbug.com/642141
       "96FF2FFA5C9173C76D47184B3E86D267B37781DE",  // http://crbug.com/642141
-      "0136FCB13DB29FD5CD442F56E59E53B61F1DF96F"   // http://crbug.com/642141
+      "0136FCB13DB29FD5CD442F56E59E53B61F1DF96F",  // http://crbug.com/642141
+      "CBCC42ABED43A4B58FE3810E62AFFA010EB0349F"   // PDF Viewer
     ]
   },
   "nativeMessaging": {