Change webkit/{fileapi,quota} code to use TaskRunner.

webkit/fileapi/file_system_context.h

 // Copyright (c) 2012 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 WEBKIT_FILEAPI_FILE_SYSTEM_CONTEXT_H_
 #define WEBKIT_FILEAPI_FILE_SYSTEM_CONTEXT_H_
 
 #include <string>
 
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/platform_file.h"
 #include "webkit/fileapi/file_system_types.h"
 #include "webkit/quota/special_storage_policy.h"
 
 class FilePath;
 class GURL;
 
 namespace base {
-class MessageLoopProxy;
+class SingleThreadTaskRunner;
+class TaskRunner;
 }
 
 namespace quota {
 class QuotaManagerProxy;
 }
 
 namespace webkit_blob {
 class FileReader;
 }
 
@@ skipping 10 matching lines @@
 class SandboxMountPointProvider;
 
 struct DefaultContextDeleter;
 
 // This class keeps and provides a file system context for FileSystem API.
 // An instance of this class is created and owned by profile.
 class FileSystemContext
     : public base::RefCountedThreadSafe<FileSystemContext,
                                         DefaultContextDeleter> {
  public:
+  // Given |file_task_runner| may be used for internal initialization and
+  // finalization by mount point providers.
+  // |io_task_runner| is used only for the final destruction.
   FileSystemContext(
-      scoped_refptr<base::MessageLoopProxy> file_message_loop,
-      scoped_refptr<base::MessageLoopProxy> io_message_loop,
-      scoped_refptr<quota::SpecialStoragePolicy> special_storage_policy,
+      base::SingleThreadTaskRunner* file_task_runner,

[michaeln, 2012/04/27 01:04:03]

If the intent is to eventually put these tasks on the sequenced worker pool,
does the file_task_runner want to be of type SequencedTaskRunner? By using
SingltThreadTaskRunner, I think this constrains us to
MessageLoop/MessageLoopProxy only based impls with no option to use SWP.

[kinuko, 2012/04/27 10:10:29]

I wanted to do so but couldn't find the nice RunsTasksOnCurrentThread so ended
up using SingleThreadTaskRunner (and it wasn't for regular file operations, for
which we could separately specify SWP).

Fixed.

+      base::SingleThreadTaskRunner* io_task_runner,
+      quota::SpecialStoragePolicy* special_storage_policy,
       quota::QuotaManagerProxy* quota_manager_proxy,
       const FilePath& profile_path,
       const FileSystemOptions& options);
   ~FileSystemContext();
 
   // This method can be called on any thread.
   bool DeleteDataForOriginOnFileThread(const GURL& origin_url);
   bool DeleteDataForOriginAndTypeOnFileThread(const GURL& origin_url,
                                               FileSystemType type);
 
@@ skipping 43 matching lines @@
       bool create,
       OpenFileSystemCallback callback);
 
   // Creates a new FileSystemOperation instance by cracking
   // the given filesystem URL |url| to get an appropriate MountPointProvider
   // and calling the provider's corresponding CreateFileSystemOperation method.
   // The resolved MountPointProvider could perform further specialization
   // depending on the filesystem type pointed by the |url|.
   FileSystemOperationInterface* CreateFileSystemOperation(
       const GURL& url,
-      base::MessageLoopProxy* file_proxy);
+      base::TaskRunner* file_task_runner);

[michaeln, 2012/04/27 01:04:03]

Since an operation may involve multiple steps, would it make sense to provide a
SequencedTaskRunner here so the 'op' gets a guarantee of the order of those
steps.

Also SequencedWorkerPoolSequencedTaskRunner's RunsTasksOnCurrentThread method
provides some nice utility similar to IsRunningOnThread semantics that generic
TaskRunner wont necessaritly provide.

[kinuko, 2012/04/27 10:10:29]

Done.  (Removed this parameter in favor of using the runner given at the
constructor time, assuming it must be ok)

 
   // Creates new FileReader instance to read a file pointed by the given
   // filesystem URL |url| starting from |offset|.
   // This method internally cracks the |url|, get an appropriate
   // MountPointProvider for the URL and call the provider's CreateFileReader.
   // The resolved MountPointProvider could perform further specialization
   // depending on the filesystem type pointed by the |url|.
   webkit_blob::FileReader* CreateFileReader(
       const GURL& url,
       int64 offset,
-      base::MessageLoopProxy* file_proxy);
+      base::TaskRunner* file_task_runner);

[michaeln, 2012/04/27 01:04:03]

ditto

[kinuko, 2012/04/27 10:10:29]

Done.

 
  private:
   friend struct DefaultContextDeleter;
   void DeleteOnCorrectThread() const;
 
-  scoped_refptr<base::MessageLoopProxy> file_message_loop_;
-  scoped_refptr<base::MessageLoopProxy> io_message_loop_;
+  scoped_refptr<base::SingleThreadTaskRunner> file_task_runner_;
+  scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
 
   scoped_refptr<quota::QuotaManagerProxy> quota_manager_proxy_;
 
   // Mount point providers.
   scoped_ptr<SandboxMountPointProvider> sandbox_provider_;
   scoped_ptr<IsolatedMountPointProvider> isolated_provider_;
   scoped_ptr<ExternalFileSystemMountPointProvider> external_provider_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(FileSystemContext);
 };
 
 struct DefaultContextDeleter {
   static void Destruct(const FileSystemContext* context) {
     context->DeleteOnCorrectThread();
   }
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_FILEAPI_FILE_SYSTEM_CONTEXT_H_