[Extensions] Observe unloading extensions in the TabHelper

chrome/browser/extensions/tab_helper.cc

Index: chrome/browser/extensions/tab_helper.cc
diff --git a/chrome/browser/extensions/tab_helper.cc b/chrome/browser/extensions/tab_helper.cc
index 67fd240c883c4dd761db88f9da40670cdf557817..bc92af0b88af50c8d971f4b81f97573ccb8a3a08 100644
--- a/chrome/browser/extensions/tab_helper.cc
+++ b/chrome/browser/extensions/tab_helper.cc
@@ -84,6 +84,7 @@ TabHelper::TabHelper(content::WebContents* web_contents)
       location_bar_controller_(new LocationBarController(web_contents)),
       extension_action_runner_(new ExtensionActionRunner(web_contents)),
       webstore_inline_installer_factory_(new WebstoreInlineInstallerFactory()),
+      registry_observer_(this),
       image_loader_ptr_factory_(this),
       weak_ptr_factory_(this) {
   // The ActiveTabPermissionManager requires a session ID; ensure this
@@ -169,6 +170,13 @@ void TabHelper::SetExtensionApp(const Extension* extension) {
 
   extension_app_ = extension;
 
+  if (extension_app_) {
+    registry_observer_.Add(
+        ExtensionRegistry::Get(web_contents()->GetBrowserContext()));
+  } else {
+    registry_observer_.RemoveAll();
+  }
+
   UpdateExtensionAppIcon(extension_app_);
 
   content::NotificationService::current()->Notify(
@@ -532,6 +540,15 @@ WebContents* TabHelper::GetAssociatedWebContents() const {
   return web_contents();
 }
 
+void TabHelper::OnExtensionUnloaded(
+    content::BrowserContext* browser_context,
+    const Extension* extension,
+    UnloadedExtensionInfo::Reason reason) {
+  DCHECK(extension_app_);
+  if (extension == extension_app_)
+    SetExtensionApp(nullptr);
+}
+
 void TabHelper::GetApplicationInfo(WebAppAction action) {
   NavigationEntry* entry =
       web_contents()->GetController().GetLastCommittedEntry();