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::CheckForFilesRemoval() {

[Paweł Hajdan Jr., 2011/05/10 11:37:51]

nit: Could you add a DCHECK(BrowserThread::CureentlyOn(...)) to each of the new
methods to make it immediately obvious which thread they run on and catch any
potential misuse?

+  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->file_exists()) {
+      existing_paths.push_back(std::pair<int64, FilePath>(
+          it->first, download_item->GetTargetFilePath()));
+    }
+  }
+
+  BrowserThread::PostTask(
+      BrowserThread::FILE, FROM_HERE,
+      NewRunnableMethod(this,
+                        &DownloadManager::CheckForFilesRemovalOnFileThread,
+                        existing_paths));
+}
+
+void DownloadManager::CheckForFilesRemovalOnFileThread(
+    const PathVector& existing_paths) {
+  PathVector removed_paths;
+  for (PathVector::const_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::OnFilesRemovalDetected,
+                        removed_paths));
+}
+
+void DownloadManager::OnFilesRemovalDetected(const PathVector& removed_paths) {
+  for (PathVector::const_iterator it = removed_paths.begin();
+       it != removed_paths.end(); ++it) {
+    DownloadMap::iterator map_it = history_downloads_.find(it->first);
+    // Since all download items are registered to DownloadDOMHandler's

[Paweł Hajdan Jr., 2011/05/10 11:37:51]

nit: I'd rather remove this comment. It might become confusing if this code has
more callers, and generally it's not necessary to comment each call to
UpdateObservers.

+    // observer, we can update the display of chrome://downloads page
+    // by calling UpdateObservers()
+    if (map_it != history_downloads_.end()) {
+      DownloadItem* download_item = map_it->second;
+      download_item->set_file_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;
 }