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Unified Diff: chrome/common/extensions/docs/static/event_pages.html

Issue 10800064: Add some more info on the event page docs to explain how to switch from (Closed) Base URL: svn://svn.chromium.org/chrome/trunk/src
Patch Set: more changes Created 8 years, 5 months ago
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Index: chrome/common/extensions/docs/static/event_pages.html
diff --git a/chrome/common/extensions/docs/static/event_pages.html b/chrome/common/extensions/docs/static/event_pages.html
index 723f99ebd368e675f154534ba37ddf62257ed280..4956a5075eaf6a24e4b61ce1274f11380219ee46 100644
--- a/chrome/common/extensions/docs/static/event_pages.html
+++ b/chrome/common/extensions/docs/static/event_pages.html
@@ -58,6 +58,14 @@ popup windows) are closed.
</p>
<p>
+You can observe the lifetime of your event page by clicking
+on "View Background Pages" in Chrome's Wrench menu, or by
+opening Chrome's task manager. You can see when your event
+page loads and unloads by observing when an entry for your
+extension appears in the list of processes.
+</p>
+
+<p>
Once the event page has been idle a short time
(a few seconds), the
<code><a href="runtime.html#event-onSuspend">chrome.runtime.onSuspend</a></code>
@@ -65,3 +73,51 @@ event is dispatched. The event page has a few more seconds to handle this
event before it is forcibly unloaded. Note that once the event is dispatched,
new activity will not keep the event page open.
</p>
+
+<h2 id="transition">Convert background page to event page</h2>
+<p>
+Follow this checklist to convert your extension's
+(persistent) background page to an event page.
+
+<ol>
+ <li>Add <code>"persistent": false</code> to your manifest as shown above.
+
+ <li>Register to receive any events your extension is interested in
+ each time the event page is loaded. The event page will be loaded once
+ for each new version of your extension. After that it will only be
+ loaded to deliver events you have registered for.
+
+ <li>If you need to do some initialization when your extension is
+ installed or upgraded, listen to the
+ <code><a href="runtime.html#event-onInstalled">chrome.runtime.onInstalled</a></code>
+ event.
+
+ <li>If you need to keep runtime state in memory throughout a browser
+ session, use the <a href="storage.html">storage API</a> or
+ IndexedDB. Since the event page does not stay loaded for long, you
+ can no longer rely on global variables for runtime state.
+
+ <li>Listen to the
+ <code><a href="runtime.html#event-onSuspend">chrome.runtime.onSuspend</a></code>
+ event if you need to do last second cleanup before your event page
+ is shut down. However, we recommend persisting periodically instead.
+ That way if your extension crashes without receiving
+ <code>onSuspend</code>, no data will typically be lost.
+
+ <li>If your extension uses <code>window.setTimeout()</code> or
+ <code>window.setInterval()</code>, switch to using the
+ <a href="alarms.html">alarms API</a> instead. DOM-based timers won't
+ be honored if the event page shuts down.
+
+ <li>If your extension uses,
+ <code><a href="extension.html#method-getBackgroundPage">chrome.extension.getBackgroundPage()</a></code>,
+ switch to
+ <code><a href="runtime.html#method-getBackgroundPage">chrome.runtime.getBackgroundPage()</a></code>
+ instead. The newer method is asynchronous so that it can start the event
+ page if necessary before returning it.
+
+ <li>If you're using <a href="messaging.html">message passing</a>, be sure
+ to close unused message ports. The event page will not shut down until all
+ message ports are closed.
+</ol>
+</p>
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