Add chrome.runtime.getPackageDirectoryEntry.

chrome/common/extensions/api/runtime.json

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 [
   {
     "namespace": "runtime",
     "documentation_permissions_required": ["runtime"],
     "types": [
       {
@@ skipping 273 matching lines @@
                   "nacl_arch" : {
                     "description": "The native client architecture. This may be different from arch on some platforms.",
                     "type": "string",
                     "enum": ["arm", "x86-32", "x86-64"]
                   }
                 }
               }
             ]
           }
         ]
+      },
+      {
+        "name": "getPackageDirectoryEntry",
+        "type": "function",
+        "description": "Returns a DirectoryEntry for the package directory.",
+        "parameters": [
+          {
+            "type": "function",
+            "name": "callback",
+            "parameters": [
+              {
+                "name": "directoryEntry",
+                "type": "object",
+                "additionalProperties": { "type": "any" },
+                "isInstanceOf": "DirectoryEntry"
+              }
+            ]
+          }
+        ]
       }
     ],
     "events": [
       {
         "name": "onStartup",
         "type": "function",
         "description": "Fired when a profile that has this extension installed first starts up. This event is not fired when an incognito profile is started, even if this extension is operating in 'split' incognito mode."
       },
       {
         "name": "onInstalled",
@@ skipping 104 matching lines @@
           "optional": "true",
           "description": "Return true from the event listener if you wish to call <code>sendResponse</code> after the event listener returns."
         }
       }
 
 
 
     ]
   }
 ]