[websql] Guard against vfs method deprecation.

third_party/WebKit/Source/modules/webdatabase/sqlite/SQLiteFileSystemWin.cpp

Index: third_party/WebKit/Source/modules/webdatabase/sqlite/SQLiteFileSystemWin.cpp
diff --git a/third_party/WebKit/Source/modules/webdatabase/sqlite/SQLiteFileSystemWin.cpp b/third_party/WebKit/Source/modules/webdatabase/sqlite/SQLiteFileSystemWin.cpp
index b8e9c55068d76e77cb09dbd0a23f89ef1b1c40d6..a2a9954ee5ab0a3b766026c4e6eb9a27e0c2808e 100644
--- a/third_party/WebKit/Source/modules/webdatabase/sqlite/SQLiteFileSystemWin.cpp
+++ b/third_party/WebKit/Source/modules/webdatabase/sqlite/SQLiteFileSystemWin.cpp
@@ -158,8 +158,7 @@ int chromiumCurrentTime(sqlite3_vfs *vfs, double *prNow)
 
 int chromiumGetLastError(sqlite3_vfs *vfs, int e, char* s)
 {
-    sqlite3_vfs* wrappedVfs = static_cast<sqlite3_vfs*>(vfs->pAppData);
-    return wrappedVfs->xGetLastError(wrappedVfs, e, s);
+    return SQLITE_ERROR;

[michaeln, 2016/01/26 21:59:34]

What's going on with this function? Can you update the comment about it too.

[Scott Hess - ex-Googler, 2016/01/26 23:44:24]

OK.

SQLite introduced this at one point and then never used it, so it seemed safer
to fail safe rather than depend on the underlying VFS implementation.  The
current os_unix.c implementation returns 0 (SQLITE_OK) and says it is never
called (and it was removed entirely at the same time as unixGetCurrentTime).

Hmm.  Your question caused me to look over at the os_win.c implementation.  It
basically returns FormatMessage() results, though it's still never called.  The
docs there do indicate that returning 0 with an empty buffer is an appropriate
implementation.  So going with that.

[The online docs list xGetLastError with no description at all :-).]

 }
 
 } // namespace
@@ -167,6 +166,13 @@ int chromiumGetLastError(sqlite3_vfs *vfs, int e, char* s)
 void SQLiteFileSystem::registerSQLiteVFS()
 {
     sqlite3_vfs* wrappedVfs = sqlite3_vfs_find("win32");
+
+    // These are implemented by delegating to |wrappedVfs|.
+    // TODO(shess): Implement local versions.
+    ASSERT(wrappedVfs->xRandomness);
+    ASSERT(wrappedVfs->xSleep);
+    ASSERT(wrappedVfs->xCurrentTime);
+
     static sqlite3_vfs chromium_vfs = {
         1,
         wrappedVfs->szOsFile,