Limit the number of captured events held by about:net-internals.

chrome/browser/resources/net_internals/capture_view.html

 <div id=capture-view-tab-content class=content-box>
   <h2>Capture options</h2>
+
+  <input id=capture-view-limit-checkbox type=checkbox />
+  <label for='capture-view-limit-checkbox'>
+    Discard old data under memory pressure.
+    <i>(If you capture all events for a long time, it is possible to exhaust memory and crash. Throwing out older data avoids this problem.)</i>
+  </label>
+
+  <p />
+
   <input id=capture-view-byte-logging-checkbox type=checkbox />
   <label for='capture-view-byte-logging-checkbox'>
     Include the actual bytes sent/received.
     <i>(This will result in huge log files, and can expose sensitive data)</i>
   </label>
 
   <ul>
     <li>
     <b>TIP</b>: <a href="#" id=capture-view-tip-anchor>logging from the command line</a>.
 
     <div style="display:none; margin-top: 10px" id=capture-view-tip-div>
       Another way to capture network events is by using the command line flag:
       <blockquote>
         --log-net-log=<i>FILENAME</i> [ --net-log-level=<i>NUMBER</i> ]
       </blockquote>
       This will stream the network events directly to a file of your choosing. If you additionally want it to log the network bytes, then pass --net-log-level=0.
     </div>
 
     </li>
   </ul>
 
 </div>