Bug 1182996 - Fix and add missing namespace comments. rs=ehsan

The bulk of this commit was generated by running:

  run-clang-tidy.py \
    -checks='-*,llvm-namespace-comment' \
    -header-filter=^/.../mozilla-central/.* \
    -fix

storage/FileSystemModule.cpp

@@ -267,7 +267,7 @@ int RowId(sqlite3_vtab_cursor* aCursor, sqlite3_int64* aRowid)
   return SQLITE_OK;
 }
 
-} // anonymous namespace
+} // namespace
 
 namespace mozilla {
 namespace storage {