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

chrome/browser/media_galleries/fileapi/safe_picasa_albums_indexer.h

 // 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.
 
 #ifndef CHROME_BROWSER_MEDIA_GALLERIES_FILEAPI_SAFE_PICASA_ALBUMS_INDEXER_H_
 #define CHROME_BROWSER_MEDIA_GALLERIES_FILEAPI_SAFE_PICASA_ALBUMS_INDEXER_H_
 
 #include <queue>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
+#include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "chrome/common/media_galleries/picasa_types.h"
+#include "content/public/browser/utility_process_host.h"
 #include "content/public/browser/utility_process_host_client.h"
 
 namespace base {
 class FilePath;
 }
 
 namespace IPC {
 class Message;
 }
 
 namespace picasa {
 
 // SafePicasaAlbumsIndexer indexes the contents of Picasa Albums by parsing the
 // INI files found in Folders. The SafePicasaAlbumsIndexer object is ref-counted
 // and kept alive after Start() is called until the ParserCallback is called.
 // The ParserCallback is guaranteed to be called eventually either when the
 // utility process replies or when it dies.
 class SafePicasaAlbumsIndexer : public content::UtilityProcessHostClient {
  public:
-  typedef base::Callback<void(bool success,
+  // Callback includes a refptr to itself to guarantee that this object
+  // survives past the execution of its last posted callback.
+  typedef base::Callback<void(scoped_refptr<SafePicasaAlbumsIndexer>,
+                              bool success,
                               const picasa::AlbumImagesMap&)> DoneCallback;
 
   SafePicasaAlbumsIndexer(const AlbumMap& albums,
                           const AlbumMap& folders,
                           const DoneCallback& callback);
 
   void Start();
 
  private:
   enum ParserState {
@@ skipping 23 matching lines @@
   virtual void OnProcessCrashed(int exit_code) OVERRIDE;
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
 
   AlbumUIDSet album_uids_;
 
   // List of folders that still need their INI files read.
   std::queue<base::FilePath> folders_queue_;
 
   std::vector<picasa::FolderINIContents> folders_inis_;
 
+  // Only accessed on the IO thread.
+  base::WeakPtr<content::UtilityProcessHost> utility_process_host_;

[vandebo (ex-Chrome), 2013/07/12 18:29:59]

This isn't used in this CL?

[tommycli, 2013/07/12 21:37:19]

This is an aborted attempt to make the utility processes explicitly
cancellable/killable. It looks to be a somewhat sizable change, so i'm backing
off and putting it in a separate CL.

+
   // Only accessed on the Media Task Runner.
   const DoneCallback callback_;
 
   // Verifies the messages from the utility process came at the right time.
   // Initialized on the Media Task Runner, but only accessed on the IO thread.
   ParserState parser_state_;
 
   base::WeakPtrFactory<SafePicasaAlbumsIndexer> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SafePicasaAlbumsIndexer);
 };
 
 }  // namespace picasa
 
 #endif  // CHROME_BROWSER_MEDIA_GALLERIES_FILEAPI_SAFE_PICASA_ALBUMS_INDEXER_H_