Fix the dynamic browser action setIcon path to work with any size icon.

chrome/common/extensions/api/browser_action.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": "browserAction",
     "description": "Use browser actions to put icons in the main Google Chrome toolbar, to the right of the address bar. In addition to its <a href='browserAction#icon'>icon</a>, a browser action can also have a <a href='browserAction#tooltip'>tooltip</a>, a <a href='browserAction#badge'>badge</a>, and a <a href='browserAction#popups'>popup</a>.",
     "types": [
       {
@@ skipping 73 matching lines @@
         "parameters": [
           {
             "name": "details",
             "type": "object",
             "properties": {
               "imageData": {
                 "choices": [
                   { "$ref": "ImageDataType" },
                   {
                     "type": "object",
-                    "properties": {
-                      "19": {"$ref": "ImageDataType", "optional": true},
-                      "38": {"$ref": "ImageDataType", "optional": true}
-                     }
+                    "additionalProperties": { "type": "any" }
                   }
                 ],
                 "optional": true,
                 "description": "Either an ImageData object or a dictionary {size -> ImageData} representing icon to be set. If the icon is specified as a dictionary, the actual image to be used is chosen depending on screen's pixel density. If the number of image pixels that fit into one screen space unit equals <code>scale</code>, then image with size <code>scale</code> * 19 will be selected. Initially only scales 1 and 2 will be supported. At least one image must be specified. Note that 'details.imageData = foo' is equivalent to 'details.imageData = {'19': foo}'"

[Evan Stade, 2016/01/13 18:35:41]

self review: should update these comments

               },
               "path": {
                 "choices": [
                   { "type": "string" },
                   {
                     "type": "object",
-                    "properties": {
-                      "19": {"type": "string", "optional": true},
-                      "38": {"type": "string", "optional": true}
-                    }
+                    "additionalProperties": { "type": "any" }
                   }
                 ],
                 "optional": true,
                 "description": "Either a relative image path or a dictionary {size -> relative image path} pointing to icon to be set. If the icon is specified as a dictionary, the actual image to be used is chosen depending on screen's pixel density. If the number of image pixels that fit into one screen space unit equals <code>scale</code>, then image with size <code>scale</code> * 19 will be selected. Initially only scales 1 and 2 will be supported. At least one image must be specified. Note that 'details.path = foo' is equivalent to 'details.imageData = {'19': foo}'"
               },
               "tabId": {
                 "type": "integer",
                 "optional": true,
                 "description": "Limits the change to when a particular tab is selected. Automatically resets when the tab is closed."
               }
@@ skipping 219 matching lines @@
         "parameters": [
           {
             "name": "tab",
             "$ref": "tabs.Tab"
           }
         ]
       }
     ]
   }
 ]