Stop accumulating event handlers for the serviceworker-internals buttons.

Each time you hit "start" or "stop" etc. in chrome://serviceworker-internals
the registration process is rerun, adding an addEventListener to each button
for each existing callback, causing a quadratic increase in event listeners.

This CL only allows the event to be registered once per button.

BUG=

Review URL: https://codereview.chromium.org/204573003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@258118 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 4 insertions, 1 deletions

diff --git a/content/browser/resources/service_worker/serviceworker_internals.js b/content/browser/resources/service_worker/serviceworker_internals.js
index 1f81379..cacbd9c 100644
--- a/content/browser/resources/service_worker/serviceworker_internals.js
+++ b/content/browser/resources/service_worker/serviceworker_internals.js
@@ -73,7 +73,10 @@ cr.define('serviceworker', function() {
             var handler = commandHandler(COMMANDS[i]);
             var links = container.querySelectorAll('button.' + COMMANDS[i]);
             for (var j = 0; j < links.length; ++j) {
-                links[j].addEventListener('click', handler, false);
+                if (!links[j].hasClickEvent) {
+                    links[j].addEventListener('click', handler, false);
+                    links[j].hasClickEvent = true;
+                }
             }
         }
     }