Resubmit of 149313003: Significantly cleans up the ImageWriter Operation class and subclasses.

chrome/browser/extensions/api/image_writer_private/destroy_partitions_operation.cc

 // Copyright 2014 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 "base/file_util.h"
 #include "chrome/browser/extensions/api/image_writer_private/destroy_partitions_operation.h"
 #include "chrome/browser/extensions/api/image_writer_private/error_messages.h"
 
 namespace extensions {
 namespace image_writer {
 
 // Number of bytes for the maximum partition table size.  By wiping this many
 // bytes we can essentially guarantee the header and associated information will
 // be wiped. See http://crbug.com/328246 for more information.
 const int kPartitionTableSize = 1 * 1024;
 
 DestroyPartitionsOperation::DestroyPartitionsOperation(
     base::WeakPtr<OperationManager> manager,
     const ExtensionId& extension_id,
     const std::string& storage_unit_id)
-    : Operation(manager, extension_id, storage_unit_id) {
-  verify_write_ = false;
-}
+    : Operation(manager, extension_id, storage_unit_id) {}
 
 DestroyPartitionsOperation::~DestroyPartitionsOperation() {}
 
-void DestroyPartitionsOperation::Start() {
-  if (!temp_dir_.CreateUniqueTempDir()) {
-    Error(error::kTempDirError);
-    return;
-  }
-
+void DestroyPartitionsOperation::StartImpl() {
   if (!base::CreateTemporaryFileInDir(temp_dir_.path(), &image_path_)) {
     Error(error::kTempFileError);
     return;
   }
 
   scoped_ptr<char[]> buffer(new char[kPartitionTableSize]);
   memset(buffer.get(), 0, kPartitionTableSize);
 
   if (file_util::WriteFile(image_path_, buffer.get(), kPartitionTableSize) !=
       kPartitionTableSize) {
     Error(error::kTempFileError);
     return;
   }
 
-  WriteStart();
+  Write(base::Bind(&DestroyPartitionsOperation::Finish, this));
 }
 
 }  // namespace image_writer
 }  // namespace extensions