chrome/browser/media_galleries/fileapi/safe_media_metadata_parser.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROME_BROWSER_MEDIA_GALLERIES_FILEAPI_SAFE_MEDIA_METADATA_PARSER_H_
   6 #define CHROME_BROWSER_MEDIA_GALLERIES_FILEAPI_SAFE_MEDIA_METADATA_PARSER_H_
   7
   8 #include "base/callback.h"
   9 #include "base/compiler_specific.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "base/memory/weak_ptr.h"
  12 #include "chrome/common/extensions/api/media_galleries.h"
  13 #include "content/public/browser/utility_process_host.h"
  14 #include "content/public/browser/utility_process_host_client.h"
  15
  16 namespace IPC {
  17 class Message;
  18 }
  19
  20 class Profile;
  21
  22 namespace metadata {
  23
  24 // Parses the media metadata of a Blob safely in a utility process. This class
  25 // expects the MIME type of the Blob to be already determined. It spawns a
  26 // utility process to do further MIME-type specific metadata extraction.
  27 // All public methods and callbacks of this class run on the UI thread.
  28 class SafeMediaMetadataParser : public content::UtilityProcessHostClient {
  29  public:
  30   // |metadata_dictionary| is owned by the callback.
  31   typedef base::Callback<
  32       void(bool parse_success, base::DictionaryValue* metadata_dictionary)>
  33       DoneCallback;
  34
  35   SafeMediaMetadataParser(Profile* profile, const std::string& blob_uuid,
  36                           int64 blob_size, const std::string& mime_type);
  37
  38   // Should be called on the UI thread. |callback| also runs on the UI thread.
  39   void Start(const DoneCallback& callback);
  40
  41  private:
  42   enum ParserState {
  43     INITIAL_STATE,
  44     STARTED_PARSING_STATE,
  45     FINISHED_PARSING_STATE,
  46   };
  47
  48   // Private because content::UtilityProcessHostClient is ref-counted.
  49   virtual ~SafeMediaMetadataParser();
  50
  51   // Launches the utility process.  Must run on the IO thread.
  52   void StartWorkOnIOThread(const DoneCallback& callback);
  53
  54   // Notification from the utility process when it finishes parsing metadata.
  55   // Runs on the IO thread.
  56   void OnParseMediaMetadataFinished(
  57       bool parse_success,
  58       const base::DictionaryValue& metadata_dictionary);
  59
  60   // Notification when the utility process requests a byte range from the blob.
  61   // Runs on the IO thread.
  62   void OnUtilityProcessRequestBlobBytes(int64 request_id, int64 byte_start,
  63                                         int64 length);
  64
  65   // UtilityProcessHostClient implementation.
  66   // Runs on the IO thread.
  67   virtual void OnProcessCrashed(int exit_code) OVERRIDE;
  68   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
  69
  70   // All member variables are only accessed on the IO thread.
  71   Profile* const profile_;
  72   const std::string blob_uuid_;
  73   const int64 blob_size_;
  74   const std::string mime_type_;
  75
  76   DoneCallback callback_;
  77
  78   base::WeakPtr<content::UtilityProcessHost> utility_process_host_;
  79
  80   // Verifies the messages from the utility process came at the right time.
  81   // Initialized on the UI thread, but only accessed on the IO thread.
  82   ParserState parser_state_;
  83
  84   DISALLOW_COPY_AND_ASSIGN(SafeMediaMetadataParser);
  85 };
  86
  87 }  // namespace metadata
  88
  89 #endif  // CHROME_BROWSER_MEDIA_GALLERIES_FILEAPI_SAFE_MEDIA_METADATA_PARSER_H_