Support for json media types as (non-image) mime types.

Source/devtools/front_end/RequestPreviewView.js

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 65 matching lines @@
     _htmlView: function()
     {
         var dataURL = this.request.asDataURL();
         if (dataURL !== null)
             return new WebInspector.RequestHTMLView(this.request, dataURL);
     },
 
     _createPreviewView: function()
     {
         if (this.request.content) {
-            if (this.request.mimeType === "application/json") {
+            var jsonMediaTypeRE = /^application\/[^;]*\+json/;
+            if (this.request.mimeType === "application/json" || jsonMediaTypeRE.test(this.request.mimeType)) {
                 var jsonView = this._jsonView();
                 if (jsonView)
                     return jsonView;
             }
 
             if (this.request.hasErrorStatusCode()) {
                 var htmlView = this._htmlView();
                 if (htmlView)
                     return htmlView;
             }
@@ skipping 15 matching lines @@
             return this._responseView.sourceView;
 
         if (this.request.type === WebInspector.resourceTypes.Other)
             return this._createEmptyView();
 
         return WebInspector.RequestView.nonSourceViewForRequest(this.request);
     },
 
     __proto__: WebInspector.RequestContentView.prototype
 }