Bug 1364768: Part 8 - Wait for delayed startup before loading most background pages. r?aswan,zombie
We shouldn't actually need to load background pages until fairly late, except
when blocking web request listeners are used.
Prior to these patches, at least for most of the 55 cycle, all background
pages generally loaded well after the first window was shown, as a consequence
of the repeated trips through the event loop that were required to complete
the startup process. After them, they generally load much earlier, before
first paint.
In order to avoid a regression in first paint performance from these patches,
I'd like to guarantee that background pages aren't loaded prior to first paint
unless they have the webRequestBlocking permission. In the future, I'd like to
delay even those add-ons until a request is made which matches one of the
extension's origin permissions.
MozReview-Commit-ID: 7miaXZRAFSt
--- a/toolkit/components/extensions/ExtensionParent.jsm
+++ b/toolkit/components/extensions/ExtensionParent.jsm
@@ -27,16 +27,18 @@ XPCOMUtils.defineLazyModuleGetter(this,
XPCOMUtils.defineLazyModuleGetter(this, "MessageChannel",
"resource://gre/modules/MessageChannel.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "NativeApp",
"resource://gre/modules/NativeMessaging.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "NetUtil",
"resource://gre/modules/NetUtil.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "PrivateBrowsingUtils",
"resource://gre/modules/PrivateBrowsingUtils.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "RecentWindow",
+ "resource:///modules/RecentWindow.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "Schemas",
"resource://gre/modules/Schemas.jsm");
XPCOMUtils.defineLazyServiceGetter(this, "gAddonPolicyService",
"@mozilla.org/addons/policy-service;1",
"nsIAddonPolicyService");
Cu.import("resource://gre/modules/ExtensionCommon.jsm");
@@ -1002,16 +1004,38 @@ function promiseExtensionViewLoaded(brow
return new Promise(resolve => {
browser.messageManager.addMessageListener("Extension:ExtensionViewLoaded", function onLoad({data}) {
browser.messageManager.removeMessageListener("Extension:ExtensionViewLoaded", onLoad);
resolve(data.childId && ParentAPIManager.getContextById(data.childId));
});
});
}
+let _delayedStartupPromise;
+
+function promiseDelayedStartup() {
+ if (!_delayedStartupPromise) {
+ if (AppConstants.platform == "android") {
+ _delayedStartupPromise = Promise.resolve();
+ } else {
+ let win = RecentWindow.getMostRecentBrowserWindow();
+ if (win && win.delayedStartupPromise) {
+ // Create a new promise to avoid keeping the browser window's
+ // compartment alive.
+ _delayedStartupPromise = Promise.resolve(win.delayedStartupPromise);
+ }
+ if (!_delayedStartupPromise) {
+ _delayedStartupPromise = promiseObserved("browser-delayed-startup-finished").then(() => {});
+ }
+ }
+ }
+
+ return _delayedStartupPromise;
+}
+
/**
* This helper is used to subscribe a listener (e.g. in the ext-devtools API implementation)
* to be called for every ExtensionProxyContext created for an extension page given
* its related extension, viewType and browser element (both the top level context and any context
* created for the extension urls running into its iframe descendants).
*
* @param {object} params.extension
* The Extension on which we are going to listen for the newly created ExtensionProxyContext.
@@ -1080,12 +1104,13 @@ const ExtensionParent = {
let manifest = types.find(type => type.id === "WebExtensionManifest");
if (!manifest) {
throw new Error("Unable to find base manifest properties");
}
gBaseManifestProperties = Object.getOwnPropertyNames(manifest.properties);
return gBaseManifestProperties;
},
+ promiseDelayedStartup,
promiseExtensionViewLoaded,
watchExtensionProxyContextLoad,
DebugUtils,
};
--- a/toolkit/components/extensions/ext-backgroundPage.js
+++ b/toolkit/components/extensions/ext-backgroundPage.js
@@ -51,19 +51,33 @@ class BackgroundPage extends HiddenExten
}
shutdown() {
super.shutdown();
}
}
this.backgroundPage = class extends ExtensionAPI {
- onManifestEntry(entryName) {
+ async onManifestEntry(entryName) {
let {manifest} = this.extension;
+ // Unless the extension needs to be able to modify and block web
+ // requests, delay loading the background page until after the
+ // first browser window is visible and interactive.
+ if (!this.extension.hasPermission("webRequestBlocking")) {
+ await ExtensionParent.promiseDelayedStartup();
+
+ // Also wait for an idle callback, so we can avoid adding jank
+ // early in the session, as much as possible.
+ let win = Services.wm.getMostRecentWindow("navigator:browser");
+ if (win) {
+ await new Promise(resolve => win.requestIdleCallback(resolve));
+ }
+ }
+
this.bgPage = new BackgroundPage(this.extension, manifest.background);
return this.bgPage.build();
}
onShutdown() {
this.bgPage.shutdown();
}