[chromium] FileSystem mods: Changes to snapshot file creation to reduce dependencies on blobs.
This patch just alters the WebKitAPI in advance of coding to the new API in chromium and webkit
sources, defining two new virtual methods (unimplemented and uncalled). The existing API remains
in place and in use.
https://bugs.webkit.org/show_bug.cgi?id=108736

Reviewed by Darin Fisher.

Source/Platform:

* chromium/public/WebFileSystem.h:
(WebFileSystem):
(WebKit::WebFileSystem::createSnapshotFileAndReadMetadata):

Source/WebKit/chromium:

* public/WebFileSystemCallbacks.h:
(WebFileSystemCallbacks):
(WebKit::WebFileSystemCallbacks::didCreateSnapshotFile):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@141712 268f45cc-cd09-0410-ab3c-d52691b4dbfc