Detect removed files and reflect the state in chrome://downloads and the download shelf

chrome/browser/download/download_manager.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_manager.h"
 
 #include "base/callback.h"
 #include "base/file_util.h"
 #include "base/i18n/case_conversion.h"
 #include "base/logging.h"
@@ skipping 247 matching lines @@
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   // Create a client to verify download URL with safebrowsing.
   // It deletes itself after the callback.
   scoped_refptr<DownloadSBClient> sb_client = new DownloadSBClient(
       info->download_id, info->url_chain, info->referrer_url);
   sb_client->CheckDownloadUrl(
       info, NewCallback(this, &DownloadManager::CheckDownloadUrlDone));
 }
 
+void DownloadManager::CheckExistingPaths() {
+  PathVector existing_paths;
+  for (DownloadMap::iterator it = history_downloads_.begin();
+       it != history_downloads_.end(); ++it) {
+    DownloadItem* download_item = it->second;
+    if (download_item->IsComplete() && download_item->is_path_exists()) {
+      existing_paths.push_back(std::pair<int64, FilePath>(
+          it->first, download_item->GetTargetFilePath()));
+    }
+  }
+
+  BrowserThread::PostTask(
+      BrowserThread::FILE, FROM_HERE,
+      NewRunnableMethod(this,
+                        &DownloadManager::CheckExistingPathsOnFileThread,
+                        existing_paths));
+}
+
+void DownloadManager::CheckExistingPathsOnFileThread(
+    PathVector existing_paths) {
+  PathVector removed_paths;
+  for (PathVector::iterator it = existing_paths.begin();
+       it != existing_paths.end(); ++it) {
+    if (!file_util::PathExists(it->second)) {
+      removed_paths.push_back(std::pair<int64, FilePath>(
+          it->first, it->second));
+    }
+  }
+
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      NewRunnableMethod(this,
+                        &DownloadManager::OnExistingPathsAvailable,
+                        removed_paths));
+}
+
+void DownloadManager::OnExistingPathsAvailable(PathVector removed_paths) {
+  for (PathVector::iterator it = removed_paths.begin();
+       it != removed_paths.end(); ++it) {
+    DownloadMap::iterator map_it = history_downloads_.find(it->first);
+    if (map_it != history_downloads_.end()) {
+      DownloadItem* download_item = map_it->second;
+      download_item->set_is_path_exists(false);
+      download_item->UpdateObservers();
+    }
+  }
+}
+
 void DownloadManager::CheckDownloadUrlDone(DownloadCreateInfo* info,
                                            bool is_dangerous_url) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(info);
 
   info->is_dangerous_url = is_dangerous_url;
 
   // Check whether this download is for an extension install or not.
   // Allow extensions to be explicitly saved.
   if (!info->prompt_user_for_save_location) {
@@ skipping 897 matching lines @@
     observed_download_manager_->RemoveObserver(this);
 }
 
 void DownloadManager::OtherDownloadManagerObserver::ModelChanged() {
   observing_download_manager_->NotifyModelChanged();
 }
 
 void DownloadManager::OtherDownloadManagerObserver::ManagerGoingDown() {
   observed_download_manager_ = NULL;
 }