Introduce AsyncFileUtil and deprecate FileSystemFileUtilProxy

In LocalFileSystemOperation we used to use a synchronous implementation
(implemented as FileSystemFileUtil) to perform subtasks (e.g. file_util::Copy
type operation), but it's not always natural to have synchronous
implementation depending on filesystem types. For example async interface
works much better if we need to talk to a remote server or a device.

This patch introduces an async version of FileUtil, AsyncFileUtil,
and replaces FileSystemFileUtil+Proxy implementation with it.

After this patch, each filesystem can choose either:
- implement synchronous FileSystemFileUtil and use it with AsyncFileUtilAdapter, or
- directly implement asynchronous AsyncFileUtil

BUG=154835
TEST=existing tests

Review URL: https://codereview.chromium.org/12035049

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@179299 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 6 insertions, 0 deletions

diff --git a/webkit/fileapi/file_system_mount_point_provider.h b/webkit/fileapi/file_system_mount_point_provider.h
index 24c00fe..7d45844 100644
--- a/webkit/fileapi/file_system_mount_point_provider.h
+++ b/webkit/fileapi/file_system_mount_point_provider.h
@@ -21,6 +21,7 @@ class FileStreamReader;
 
 namespace fileapi {
 
+class AsyncFileUtil;
 class FileSystemURL;
 class FileStreamWriter;
 class FileSystemContext;
@@ -67,8 +68,13 @@ class WEBKIT_STORAGE_EXPORT FileSystemMountPointProvider {
   virtual bool IsRestrictedFileName(const FilePath& filename) const = 0;
 
   // Returns the specialized FileSystemFileUtil for this mount point.
+  // It is ok to return NULL if the filesystem doesn't support synchronous
+  // version of FileUtil.
   virtual FileSystemFileUtil* GetFileUtil(FileSystemType type) = 0;
 
+  // Returns the specialized AsyncFileUtil for this mount point.
+  virtual AsyncFileUtil* GetAsyncFileUtil(FileSystemType type) = 0;
+
   // Returns file permission policy we should apply for the given |url|.
   virtual FilePermissionPolicy GetPermissionPolicy(
       const FileSystemURL& url,