Media Galleries API Picasa: Make PicasaDataProvider handle async PMP and INI parsing robustly.

chrome/browser/media_galleries/fileapi/safe_picasa_albums_indexer.cc

 // Copyright 2013 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/media_galleries/fileapi/safe_picasa_albums_indexer.h"
 
 #include "base/file_util.h"
 #include "chrome/browser/media_galleries/fileapi/media_file_system_backend.h"
 #include "chrome/common/chrome_utility_messages.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/child_process_data.h"
 #include "content/public/browser/utility_process_host.h"
 
 using chrome::MediaFileSystemBackend;
 using content::BrowserThread;
 using content::UtilityProcessHost;
 
 namespace picasa {
 
 namespace {
 
+// Arbitrarily chosen to be a decent size but not block thread too much.
+const int kPicasaINIReadBatchSize = 10;
+
+}  // namespace
+
 // Picasa INI files are named "picasa.ini" on Picasa for Windows before version
 // 71.18. Later versions and Picasa for Mac uses ".picasa.ini".
 // See: https://support.google.com/picasa/answer/11257?hl=en
 const char kPicasaINIFilename[]       = ".picasa.ini";
 const char kPicasaINIFilenameLegacy[] = "picasa.ini";
 
-// Arbitrarily chosen to be a decent size but not block thread too much.
-const int kPicasaINIReadBatchSize = 10;
-
-}  // namespace
-
-SafePicasaAlbumsIndexer::SafePicasaAlbumsIndexer(
-    const AlbumMap& albums,
-    const AlbumMap& folders,
-    const DoneCallback& callback)
-    : callback_(callback),
-      parser_state_(INITIAL_STATE) {
+SafePicasaAlbumsIndexer::SafePicasaAlbumsIndexer(const AlbumMap& albums,
+                                                 const AlbumMap& folders)
+    : parser_state_(INITIAL_STATE) {
   DCHECK(MediaFileSystemBackend::CurrentlyOnMediaTaskRunnerThread());
-  DCHECK(!callback_.is_null());
 
   folders_inis_.reserve(folders.size());
 
   for (AlbumMap::const_iterator it = albums.begin(); it != albums.end(); ++it)
     album_uids_.insert(it->second.uid);
 
   for (AlbumMap::const_iterator it = folders.begin(); it != folders.end(); ++it)
     folders_queue_.push(it->second.path);
 }
 
-void SafePicasaAlbumsIndexer::Start() {
+void SafePicasaAlbumsIndexer::Start(const DoneCallback& callback) {
   DCHECK(MediaFileSystemBackend::CurrentlyOnMediaTaskRunnerThread());
+  DCHECK(!callback.is_null());
 
+  callback_ = callback;
   ProcessFoldersBatch();
 }
 
 SafePicasaAlbumsIndexer::~SafePicasaAlbumsIndexer() {
 }
 
 void SafePicasaAlbumsIndexer::ProcessFoldersBatch() {
   DCHECK(MediaFileSystemBackend::CurrentlyOnMediaTaskRunnerThread());
 
   for (int i = 0; i < kPicasaINIReadBatchSize && !folders_queue_.empty(); ++i) {
@@ skipping 38 matching lines @@
       UtilityProcessHost::Create(this, base::MessageLoopProxy::current());
   host->EnableZygote();
   host->Send(new ChromeUtilityMsg_IndexPicasaAlbumsContents(album_uids_,
                                                             folders_inis_));
   parser_state_ = STARTED_PARSING_STATE;
 }
 
 void SafePicasaAlbumsIndexer::OnIndexPicasaAlbumsContentsFinished(
     const AlbumImagesMap& albums_images) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  DCHECK(!callback_.is_null());
   if (parser_state_ != STARTED_PARSING_STATE)
     return;
 
   MediaFileSystemBackend::MediaTaskRunner()->PostTask(
       FROM_HERE,
       base::Bind(callback_, true, albums_images));
   parser_state_ = FINISHED_PARSING_STATE;
 }
 
 void SafePicasaAlbumsIndexer::OnProcessCrashed(int exit_code) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  DCHECK(!callback_.is_null());
 
   MediaFileSystemBackend::MediaTaskRunner()->PostTask(
       FROM_HERE,
       base::Bind(callback_, false, AlbumImagesMap()));
 }
 
 bool SafePicasaAlbumsIndexer::OnMessageReceived(
     const IPC::Message& message) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(SafePicasaAlbumsIndexer, message)
     IPC_MESSAGE_HANDLER(
         ChromeUtilityHostMsg_IndexPicasaAlbumsContents_Finished,
         OnIndexPicasaAlbumsContentsFinished)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   return handled;
 }
 
 }  // namespace picasa