re-use WebUIs

chrome/browser/ui/webui/downloads_dom_handler.cc

 // Copyright (c) 2012 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/ui/webui/downloads_dom_handler.h"
 
 #include <algorithm>
 #include <functional>
 
 #include "base/basictypes.h"
@@ skipping 74 matching lines @@
                             event,
                             DOWNLOADS_DOM_EVENT_MAX);
 }
 
 }  // namespace
 
 DownloadsDOMHandler::DownloadsDOMHandler(content::DownloadManager* dlm)
     : search_text_(),
       download_manager_(dlm),
       original_profile_download_manager_(NULL),
+      initialized_(false),
       ALLOW_THIS_IN_INITIALIZER_LIST(weak_ptr_factory_(this)) {
   // Create our fileicon data source.
   Profile* profile = Profile::FromBrowserContext(dlm->GetBrowserContext());
   ChromeURLDataManager::AddDataSource(profile, new FileIconSource());
 
   // Figure out our parent DownloadManager, if any.
   Profile* original_profile = profile->GetOriginalProfile();
   if (original_profile != profile) {
     original_profile_download_manager_ = DownloadServiceFactory::GetForProfile(
         original_profile)->GetDownloadManager();
   }
 }
 
 DownloadsDOMHandler::~DownloadsDOMHandler() {
   ClearDownloadItems();
   download_manager_->RemoveObserver(this);
   if (original_profile_download_manager_)
     original_profile_download_manager_->RemoveObserver(this);
 }
 
 // DownloadsDOMHandler, public: -----------------------------------------------
 
 void DownloadsDOMHandler::OnPageLoaded(const base::ListValue* args) {
+  if (initialized_)
+    return;
+  initialized_ = true;
+
   download_manager_->AddObserver(this);
   if (original_profile_download_manager_)
     original_profile_download_manager_->AddObserver(this);
 }
 
 void DownloadsDOMHandler::RegisterMessages() {
   web_ui()->RegisterMessageCallback("onPageLoaded",
       base::Bind(&DownloadsDOMHandler::OnPageLoaded,
                  base::Unretained(this)));
   web_ui()->RegisterMessageCallback("getDownloads",
@@ skipping 274 matching lines @@
 }
 
 content::DownloadItem* DownloadsDOMHandler::GetDownloadByValue(
     const ListValue* args) {
   int id;
   if (ExtractIntegerValue(args, &id)) {
     return GetDownloadById(id);
   }
   return NULL;
 }