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.cc b/webkit/browser/fileapi/test_file_system_backend.cc
index 4df22b7..547d6eb 100644
--- a/webkit/browser/fileapi/test_file_system_backend.cc
+++ b/webkit/browser/fileapi/test_file_system_backend.cc
@@ -148,12 +148,14 @@
   return (type == kFileSystemTypeTest);
 }
 
-void TestFileSystemBackend::InitializeFileSystem(
+void TestFileSystemBackend::Initialize(FileSystemContext* context) {
+}
+
+void TestFileSystemBackend::OpenFileSystem(
     const GURL& origin_url,
     FileSystemType type,
     OpenFileSystemMode mode,
-    FileSystemContext* context,
-    const InitializeFileSystemCallback& callback) {
+    const OpenFileSystemCallback& callback) {
   callback.Run(GetFileSystemRootURI(origin_url, type),
                GetFileSystemName(origin_url, type),
                base::PLATFORM_FILE_OK);