OOP PDF: Set the pdf extension URL permissions to <all_urls>.

Currently, the PDF extension isn't permitted access to paths to network
mounts (e.g. file://network_share/path.pdf). A permission of <all_urls>
allows access to such URLs.

BUG=452319

Review URL: https://codereview.chromium.org/880773002

Cr-Commit-Position: refs/heads/master@{#313215}

chrome/browser/resources/pdf/manifest-common.json.unflattened

@@ -7,11 +7,7 @@
   "offline_enabled": true,
   "incognito": "split",
   "permissions": [
-    "file://*/",
-    "ftp://*/",
-    "http://*/",
-    "https://*/",
-    "chrome://*/"
+    "<all_urls>"
   ],
   "mime_types": [
     "application/pdf"