Consistently use notifications from component updater w/ on-demand PNaCl.

chrome/browser/component_updater/pnacl/pnacl_updater_observer.cc

 // Copyright (c) 2013 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.
 
 #include "chrome/browser/component_updater/pnacl/pnacl_updater_observer.h"
 
-#include "base/logging.h"
-#include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/component_updater/pnacl/pnacl_component_installer.h"
-#include "content/public/browser/notification_service.h"
+#include "content/public/browser/browser_thread.h"
 
-PnaclUpdaterObserver::PnaclUpdaterObserver(
-    PnaclComponentInstaller* installer) : pnacl_installer_(installer) {
-  registrar_.Add(this,
-                 chrome::NOTIFICATION_COMPONENT_UPDATER_SLEEPING,
-                 content::NotificationService::AllSources());
+using content::BrowserThread;
+
+PnaclUpdaterObserver::PnaclUpdaterObserver(PnaclComponentInstaller* pci)
+    : must_observe_(false), pnacl_installer_(pci) {}
+
+PnaclUpdaterObserver::~PnaclUpdaterObserver() {}
+
+void PnaclUpdaterObserver::EnsureObserving() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  must_observe_ = true;
 }
 
-PnaclUpdaterObserver::~PnaclUpdaterObserver() { }
+void PnaclUpdaterObserver::StopObserving() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  must_observe_ = false;
+}
 
-void PnaclUpdaterObserver::Observe(
-    int type,
-    const content::NotificationSource& source,
-    const content::NotificationDetails& details) {
-  if (type == chrome::NOTIFICATION_COMPONENT_UPDATER_SLEEPING) {
-    // If the component updater sleeps before a NotifyInstallSuccess,
-    // then requests for installs were likely skipped, or an error occurred.
-    pnacl_installer_->NotifyInstallError();
-    return;
+void PnaclUpdaterObserver::OnEvent(Events event, int extra) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  if (must_observe_) {
+    switch (event) {
+      default:
+        break;
+      case COMPONENT_UPDATE_READY:
+        // If the component updater says there is an UPDATE_READY w/ source
+        // being the PNaCl ID, then installation is handed off to the PNaCl
+        // installer and we can stop observing. The installer will be the one
+        // to run the callback w/ success or failure.
+        must_observe_ = false;
+        break;
+      case COMPONENT_UPDATER_SLEEPING:
+        // If the component updater sleeps before an UPDATE_READY for this
+        // component, then requests for installs were likely skipped,
+        // an error occurred, or there was no new update.
+        must_observe_ = false;

[Sorin Jianu, 2013/08/05 19:24:58]

These could be good events to fire: skipping an install, an error, or no update.

[jvoung (off chromium), 2013/08/05 20:36:03]

That would be more direct of a signal, but we should watch out about making too
many events for the installer to consider (would also be good to not have to
worry about the events firing twice for the diff vs full issue you mention).

+        pnacl_installer_->NotifyInstallError();
+        break;
+    }
   }
 }