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

webkit/fileapi/file_system_context.h

Index: webkit/fileapi/file_system_context.h
diff --git a/webkit/fileapi/file_system_context.h b/webkit/fileapi/file_system_context.h
index d72a3ca745fdef0a1e2b6d2d962bbeca866482a3..7351b61f49334e0c5f39901398694740f0c462a6 100644
--- a/webkit/fileapi/file_system_context.h
+++ b/webkit/fileapi/file_system_context.h
@@ -18,7 +18,8 @@ class FilePath;
 class GURL;
 
 namespace base {
-class MessageLoopProxy;
+class SingleThreadTaskRunner;
+class TaskRunner;
 }
 
 namespace quota {
@@ -49,10 +50,13 @@ 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);
@@ -116,7 +120,7 @@ class FileSystemContext
   // 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|.
@@ -127,14 +131,14 @@ class FileSystemContext
   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_;