FileAPI: Add Initialize() function to FileSystemBackend

This is a preliminary change for adding SyncFileSystemBackend.

At first, we planed to do initializing process for SyncFileSystemBackend in
InitializeFileSystem(), but it revealed that there are some hassles on that
way (see [*]), so we decieded to introduce a separate initialze function and
to rename InitializeFileSystem() to its original name (i.e. OpenFileSystem()).

[*] https://codereview.chromium.org/18668003/


BUG=242422
TEST=should pass all existing tests
NOTRY=true

Review URL: https://chromiumcodereview.appspot.com/19632004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@213382 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/webkit/browser/fileapi/test_file_system_backend.h b/webkit/browser/fileapi/test_file_system_backend.h
index 21b4e433..ef252c1 100644
--- a/webkit/browser/fileapi/test_file_system_backend.h
+++ b/webkit/browser/fileapi/test_file_system_backend.h
@@ -35,12 +35,12 @@
 
   // FileSystemBackend implementation.
   virtual bool CanHandleType(FileSystemType type) const OVERRIDE;
-  virtual void InitializeFileSystem(
+  virtual void Initialize(FileSystemContext* context) OVERRIDE;
+  virtual void OpenFileSystem(
       const GURL& origin_url,
       FileSystemType type,
       OpenFileSystemMode mode,
-      FileSystemContext* context,
-      const InitializeFileSystemCallback& callback) OVERRIDE;
+      const OpenFileSystemCallback& callback) OVERRIDE;
   virtual FileSystemFileUtil* GetFileUtil(FileSystemType type) OVERRIDE;
   virtual AsyncFileUtil* GetAsyncFileUtil(FileSystemType type) OVERRIDE;
   virtual CopyOrMoveFileValidatorFactory* GetCopyOrMoveFileValidatorFactory(