fix transition from full overlays to fb

we need to clear the whole framebuffer in that situation because
we can't trust the content of the FB when partial (fb preserving)
updates are used.

Bug: 5318492

Change-Id: I3f0e01b0fb665a34e44d88ad9f0f54a5d990060b
diff --git a/services/surfaceflinger/DisplayHardware/DisplayHardware.h b/services/surfaceflinger/DisplayHardware/DisplayHardware.h
index 40a6f1e..f02c954 100644
--- a/services/surfaceflinger/DisplayHardware/DisplayHardware.h
+++ b/services/surfaceflinger/DisplayHardware/DisplayHardware.h
@@ -84,9 +84,10 @@
     
     status_t compositionComplete() const;
     
-    Rect bounds() const {
+    Rect getBounds() const {
         return Rect(mWidth, mHeight);
     }
+    inline Rect bounds() const { return getBounds(); }
 
     // only for debugging
     int getCurrentBufferIndex() const;