Delay DownloadManager creation by adding a callback queue to DownloadService

chrome/browser/download/download_service.cc

 // Copyright (c) 2011 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/download/download_service.h"
 
+#include "base/callback.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/download/chrome_download_manager_delegate.h"
 #include "chrome/browser/download/download_service_factory.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "content/browser/download/download_id_factory.h"
 #include "content/browser/download/download_manager_impl.h"
 
 DownloadService::DownloadService(Profile* profile)
     : download_manager_created_(false),
       profile_(profile) {
   if (profile_->IsOffTheRecord()) {
     id_factory_ = DownloadServiceFactory::GetForProfile(
         profile_->GetOriginalProfile())->GetDownloadIdFactory();
   } else {
     id_factory_ = new DownloadIdFactory(this);
   }
 }
 
 DownloadService::~DownloadService() {}
 
 DownloadIdFactory* DownloadService::GetDownloadIdFactory() const {
   return id_factory_.get();
 }
 
+void DownloadService::OnManagerCreated(
+    const DownloadService::OnManagerCreatedCallback& cb) {
+  if (download_manager_created_) {
+    cb.Run(manager_.get());
+  } else {
+    on_manager_created_callbacks_.push_back(cb);
+  }
+}
+
 DownloadManager* DownloadService::GetDownloadManager() {
   if (!download_manager_created_) {
     // In case the delegate has already been set by
     // SetDownloadManagerDelegateForTesting.
     if (!manager_delegate_.get())
       manager_delegate_ = new ChromeDownloadManagerDelegate(profile_);
     manager_ = new DownloadManagerImpl(
         manager_delegate_.get(),
         id_factory_.get(),
         g_browser_process->download_status_updater());
     manager_->Init(profile_);
     manager_delegate_->SetDownloadManager(manager_);
     download_manager_created_ = true;
+    for (std::vector<OnManagerCreatedCallback>::iterator cb
+         = on_manager_created_callbacks_.begin();
+         cb != on_manager_created_callbacks_.end(); ++cb) {
+      cb->Run(manager_.get());
+    }
+    on_manager_created_callbacks_.clear();
   }
   return manager_.get();
 }
 
 bool DownloadService::HasCreatedDownloadManager() {
   return download_manager_created_;
 }
 
 int DownloadService::DownloadCount() const {
   return download_manager_created_ ? manager_->InProgressCount() : 0;
@@ skipping 36 matching lines @@
     // Resetting here will guarantee that any attempts to get the
     // DownloadManager after shutdown will return null.
     //
     // TODO(rdsmith): Figure out how to guarantee when the last reference
     // will be released and make DownloadManager not RefCountedThreadSafe<>.
     manager_.release();
   }
   if (manager_delegate_.get())
     manager_delegate_.release();
 }