make sure to clear the framebuffer when using overlays

Bug: 6354761, 6353719
Change-Id: I0739de3fee7c54c14b294ffd768b70ee1f541d9e
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 1aea452..d9c2033 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -350,7 +350,7 @@
 
             void        debugFlashRegions();
             void        drawWormhole() const;
-           
+
             void listLayersLocked(const Vector<String16>& args, size_t& index,
                     String8& result, char* buffer, size_t SIZE) const;
             void dumpStatsLocked(const Vector<String16>& args, size_t& index,
@@ -402,7 +402,6 @@
 
                 // don't use a lock for these, we don't care
                 int                         mDebugRegion;
-                int                         mDebugBackground;
                 int                         mDebugDDMS;
                 int                         mDebugDisableHWC;
                 int                         mDebugDisableTransformHint;