Support asynchronous patching operations in the component updater.

chrome/browser/component_updater/component_patcher.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.
 
 // Component updates can be either differential updates or full updates.
 // Full updates come in CRX format; differential updates come in CRX-style
 // archives, but have a different magic number. They contain "commands.json", a
 // list of commands for the patcher to follow. The patcher uses these commands,
 // the other files in the archive, and the files from the existing installation
 // of the component to create the contents of a full update, which is then
@@ skipping 33 matching lines @@
 // the error code of the failing patch operation, if there is such a failure.
 class ComponentPatcher {
  public:
   // The type of a patch file.
   enum PatchType {
     kPatchTypeUnknown,
     kPatchTypeCourgette,
     kPatchTypeBsdiff,
   };
 
-  virtual ComponentUnpacker::Error Patch(PatchType patch_type,
+  virtual component_updater::Error Patch(PatchType patch_type,
                                          const base::FilePath& input_file,
                                          const base::FilePath& patch_file,
                                          const base::FilePath& output_file,
                                          int* error) = 0;
   virtual ~ComponentPatcher() {}
 };
 
 class ComponentPatcherCrossPlatform : public ComponentPatcher {
  public:
   ComponentPatcherCrossPlatform();
-  virtual ComponentUnpacker::Error Patch(PatchType patch_type,
+  virtual component_updater::Error Patch(PatchType patch_type,
                                          const base::FilePath& input_file,
                                          const base::FilePath& patch_file,
                                          const base::FilePath& output_file,
                                          int* error) OVERRIDE;
  private:
   DISALLOW_COPY_AND_ASSIGN(ComponentPatcherCrossPlatform);
 };
 
 // This function takes an unpacked differential CRX (|input_dir|) and a
 // component installer, and creates a new (non-differential) unpacked CRX, which
 // is then installed normally.
 // The non-differential files are written into the |unpack_dir| directory.
-// Sets |error| to the error code of the first failing patch operation.
-ComponentUnpacker::Error DifferentialUpdatePatch(
+// When finished, calls the callback, passing error codes if any errors were
+// encountered.
+void DifferentialUpdatePatch(
     const base::FilePath& input_dir,
     const base::FilePath& unpack_dir,
     ComponentPatcher* component_patcher,
     ComponentInstaller* installer,
-    int* error);
+    base::Callback<void(component_updater::Error, int)> callback);
 
 #endif  // CHROME_BROWSER_COMPONENT_UPDATER_COMPONENT_PATCHER_H_