Make DataSourceFactory singletone

This is preparation for having a subclass of DataSourceFactory which
is only used in mediaserver process with OMA (forward-lock) use case.

Test: build
Bug: 142567168
Change-Id: I2a1ab3d1ae89f657a84376d9a95d4e814b545b4f
diff --git a/media/codec2/components/cmds/codec2.cpp b/media/codec2/components/cmds/codec2.cpp
index e572a53..38eaf88 100644
--- a/media/codec2/components/cmds/codec2.cpp
+++ b/media/codec2/components/cmds/codec2.cpp
@@ -418,7 +418,7 @@
         const char *filename = argv[k];
 
         sp<DataSource> dataSource =
-            DataSourceFactory::CreateFromURI(nullptr /* httpService */, filename);
+            DataSourceFactory::getInstance()->CreateFromURI(nullptr /* httpService */, filename);
 
         if (strncasecmp(filename, "sine:", 5) && dataSource == nullptr) {
             fprintf(stderr, "Unable to create data source.\n");