cleanups in preparation of bigger changes

- fix typo drawForSreenshot misspelled
- get rid of DisplayDeviceBase
- removed unused or unneeded code
- always pass a DisplayDevice to Layer methods that are called
  on a per-display basis (to make it clear that this could be
  called more than once per composition).

Change-Id: Id948b7e09fe5c06db0e42d40d6ed75dd095c7f44
diff --git a/services/surfaceflinger/LayerScreenshot.cpp b/services/surfaceflinger/LayerScreenshot.cpp
index 5b7cf68..280d85f 100644
--- a/services/surfaceflinger/LayerScreenshot.cpp
+++ b/services/surfaceflinger/LayerScreenshot.cpp
@@ -18,6 +18,9 @@
 #include <stdint.h>
 #include <sys/types.h>
 
+#include <GLES/gl.h>
+#include <GLES/glext.h>
+
 #include <utils/Errors.h>
 #include <utils/Log.h>