Media Galleries API: Fix MediaGalleriesPreferences finders race.

chrome/browser/media_galleries/media_file_system_registry.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.
 
 // MediaFileSystemRegistry implementation.
 
 #include "chrome/browser/media_galleries/media_file_system_registry.h"
 
 #include <set>
 #include <vector>
@@ skipping 440 matching lines @@
       extension_hosts_map_.find(profile);
   if (extension_hosts->second.empty())
     preferences->AddGalleryChangeObserver(this);
 
   ExtensionGalleriesHost* extension_host =
       extension_hosts->second[extension->id()].get();
   if (!extension_host) {
     extension_host = new ExtensionGalleriesHost(
         file_system_context_.get(),
         base::Bind(&MediaFileSystemRegistry::OnExtensionGalleriesHostEmpty,
-                   base::Unretained(this), profile, extension->id()));
+                   base::Unretained(this),
+                   profile,
+                   extension->id()));
     extension_hosts_map_[profile][extension->id()] = extension_host;
   }
   extension_host->ReferenceFromRVH(rvh);
 
   extension_host->GetMediaFileSystems(galleries, preferences->known_galleries(),
                                       callback);
 }
 
 MediaGalleriesPreferences* MediaFileSystemRegistry::GetPreferences(
     Profile* profile) {
-  MediaGalleriesPreferences* preferences =
-      MediaGalleriesPreferencesFactory::GetForProfile(profile);
-  if (ContainsKey(extension_hosts_map_, profile))
-    return preferences;
-
-  // Create an empty entry so the initialization code below only gets called
-  // once per profile.
-  extension_hosts_map_[profile] = ExtensionHostMap();
+  // Create an empty ExtensionHostMap for this profile on first initialization.
+  if (!ContainsKey(extension_hosts_map_, profile))
+    extension_hosts_map_[profile] = ExtensionHostMap();
   media_galleries::UsageCount(media_galleries::PROFILES_WITH_USAGE);
 
-  // TODO(gbillock): Move this stanza to MediaGalleriesPreferences init code.
-  StorageMonitor* monitor = StorageMonitor::GetInstance();
-  DCHECK(monitor->IsInitialized());
-  std::vector<StorageInfo> existing_devices =
-      monitor->GetAllAvailableStorages();
-  for (size_t i = 0; i < existing_devices.size(); i++) {
-    if (!(StorageInfo::IsMediaDevice(existing_devices[i].device_id()) &&
-          StorageInfo::IsRemovableDevice(existing_devices[i].device_id())))
-      continue;
-    preferences->AddGallery(existing_devices[i].device_id(),
-                            base::FilePath(),
-                            false,
-                            existing_devices[i].storage_label(),
-                            existing_devices[i].vendor_name(),
-                            existing_devices[i].model_name(),
-                            existing_devices[i].total_size_in_bytes(),
-                            base::Time::Now());
-  }
-  return preferences;
+  return MediaGalleriesPreferencesFactory::GetForProfile(profile);
 }
 
 void MediaFileSystemRegistry::OnRemovableStorageDetached(
     const StorageInfo& info) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   // Since revoking a gallery in the ExtensionGalleriesHost may cause it
   // to be removed from the map and therefore invalidate any iterator pointing
   // to it, this code first copies all the invalid gallery ids and the
   // extension hosts in which they may appear (per profile) and revoked it in
   // a second step.
   std::vector<InvalidatedGalleriesInfo> invalid_galleries_info;
 
   for (ExtensionGalleriesHostMap::iterator profile_it =
            extension_hosts_map_.begin();
        profile_it != extension_hosts_map_.end();
        ++profile_it) {
     MediaGalleriesPreferences* preferences = GetPreferences(profile_it->first);
+    // If |preferences| is not yet initialized, it won't contain any galleries.
+    if (!preferences->IsInitialized())
+      continue;
+
     InvalidatedGalleriesInfo invalid_galleries_in_profile;
     invalid_galleries_in_profile.pref_ids =
         preferences->LookUpGalleriesByDeviceId(info.device_id());
 
     for (ExtensionHostMap::const_iterator extension_host_it =
              profile_it->second.begin();
          extension_host_it != profile_it->second.end();
          ++extension_host_it) {
       invalid_galleries_in_profile.extension_hosts.insert(
           extension_host_it->second.get());
@@ skipping 85 matching lines @@
 
     IsolatedContext::GetInstance()->RevokeFileSystem(fsid);
   }
 
  private:
   MediaFileSystemRegistry* registry_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaFileSystemContextImpl);
 };
 
+// Constructor in 'private' section because depends on private class definition.
 MediaFileSystemRegistry::MediaFileSystemRegistry()
     : file_system_context_(new MediaFileSystemContextImpl(this)) {
   StorageMonitor::GetInstance()->AddObserver(this);
 }
 
 MediaFileSystemRegistry::~MediaFileSystemRegistry() {
   // TODO(gbillock): This is needed because the unit test uses the
   // g_browser_process registry. We should create one in the unit test,
   // and then can remove this.
   if (StorageMonitor::GetInstance())
@@ skipping 97 matching lines @@
   DCHECK_EQ(1U, erase_count);
   if (extension_hosts->second.empty()) {
     // When a profile has no ExtensionGalleriesHosts left, remove the
     // matching gallery-change-watcher since it is no longer needed. Leave the
     // |extension_hosts| entry alone, since it indicates the profile has been
     // previously used.
     MediaGalleriesPreferences* preferences = GetPreferences(profile);
     preferences->RemoveGalleryChangeObserver(this);
   }
 }