Show error message on attempt to load old Timeline data into tracing based Timeline

Source/devtools/front_end/timeline/TracingTimelineModel.js

 // Copyright 2014 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.
 
 /**
  * @constructor
  * @param {!WebInspector.TracingModel} tracingModel
  * @param {!WebInspector.TimelineModel.Filter} recordFilter
  * @extends {WebInspector.TimelineModel}
  */
@@ skipping 805 matching lines @@
             lastIndex = WebInspector.TextUtils.findBalancedCurlyBrackets(data, index);
         } while (lastIndex !== -1)
 
         var json = data.slice(0, index) + "]";
         this._buffer = data.slice(index);
 
         if (!index)
             return;
 
         if (this._firstChunk) {
-            this._firstChunk = false;
             this._model.reset();
         } else {
             var commaIndex = json.indexOf(",");
             if (commaIndex !== -1)
                 json = json.slice(commaIndex + 1);
             json = "[" + json;
         }
 
         var items;
         try {
             items = /** @type {!Array.<!WebInspector.TracingModel.EventPayload>} */ (JSON.parse(json));
         } catch (e) {
-            WebInspector.console.error("Malformed timeline data.");
-            this._model.reset();
-            this._reader.cancel();
-            this._progress.done();
+            this._reportErrorAndCancelLoading("Malformed timeline data: " + e);
             return;
         }
 
-        this._loader.loadNextChunk(items);
+        if (this._firstChunk) {
+            this._firstChunk = false;
+            if (this._looksLikeAppVersion(items[0])) {
+                this._reportErrorAndCancelLoading("Old Timeline format is not supported.");
+                return;
+            }
+        }
+
+        try {
+            this._loader.loadNextChunk(items);
+        } catch(e) {
+            this._reportErrorAndCancelLoading("Malformed timeline data: " + e);
+            return;
+        }
+    },
+
+    _reportErrorAndCancelLoading: function(messsage)
+    {
+        WebInspector.console.error(messsage);
+        this._model.reset();
+        this._reader.cancel();
+        this._progress.done();
+    },
+
+    _looksLikeAppVersion: function(item)
+    {
+        return typeof item === "string" && item.indexOf("Chrome") !== -1;
     },
 
     close: function()
     {
         this._loader.finish();
     }
 }
 
 /**
  * @constructor
@@ skipping 40 matching lines @@
     },
 
     _didWriteNextChunk: function(stream)
     {
         if (this._recordIndex === this._payloads.length)
             stream.close();
         else
             this._writeNextChunk(stream);
     }
 }