Only dispatch tab events when there is someone listening

chrome/browser/extensions/extensions_service.cc

 // Copyright (c) 2009 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/extensions/extensions_service.h"
 
 #include "base/command_line.h"
 #include "base/file_util.h"
 #include "base/string_util.h"
 #include "base/values.h"
@@ skipping 109 matching lines @@
 }
 
 void ExtensionsService::Init() {
   DCHECK(!ready_);
   DCHECK_EQ(extensions_.size(), 0u);
 
   // Hack: we need to ensure the ResourceDispatcherHost is ready before we load
   // the first extension, because its members listen for loaded notifications.
   g_browser_process->resource_dispatcher_host();
 
-  // Start up the extension event routers.
-  ExtensionBrowserEventRouter::GetInstance()->Init();
-
   LoadAllExtensions();
 
   // TODO(erikkay) this should probably be deferred to a future point
   // rather than running immediately at startup.
   CheckForExternalUpdates();
 
   // TODO(erikkay) this should probably be deferred as well.
   GarbageCollectExtensions();
 }
 
@@ skipping 358 matching lines @@
                                  NotificationType::EXTENSION_OVERINSTALL_ERROR,
                                  false);
         return;
       }
     }
 
     switch (extension_prefs_->GetExtensionState(extension->id())) {
       case Extension::ENABLED:
         extensions_.push_back(scoped_extension.release());
 
+        // We delay starting up the browser event router until at least one
+        // extension that needs it is loaded.
+        if (extension->HasApiPermission(Extension::kTabPermission)) {
+          ExtensionBrowserEventRouter::GetInstance()->Init();

[Evan Martin, 2009/10/29 01:56:29]

Are you certain there's no other way for this to be created such that Init isn't
called?

[Aaron Boodman, 2009/10/29 04:03:25]

I don't understand.

[rafaelw, 2009/10/29 04:08:46]

Don't need braces

On 2009/10/29 01:56:29, Evan Martin wrote:

+        }
+
         if (extension->location() != Extension::LOAD)
           extension_prefs_->MigrateToPrefs(extension);
 
         NotifyExtensionLoaded(extension);
 
         if (extension->IsTheme() && extension->location() == Extension::LOAD) {
           NotificationService::current()->Notify(
               NotificationType::THEME_INSTALLED,
               Source<ExtensionsService>(this),
               Details<Extension>(extension));
@@ skipping 291 matching lines @@
       linked_ptr<ExternalExtensionProvider>(test_provider);
 }
 
 void ExtensionsServiceBackend::OnExternalExtensionFound(
     const std::string& id, const Version* version, const FilePath& path,
     Extension::Location location) {
   frontend_loop_->PostTask(FROM_HERE, NewRunnableMethod(frontend_,
       &ExtensionsService::OnExternalExtensionFound, id, version->GetString(),
       path, location));
 }