SurfaceFlinger: Respect the PROTECTED gralloc bit.

This change makes SurfaceFlinger treat layers for which the active
buffer has the GRALLOC_USAGE_PROTECTED bit set as if they have the
'secure' flag set.

Change-Id: Ic60b6513a63e4bb92ec6ce9fd12fd39b4ba5f674
Bug: 4081304
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index bccc900..128f93d 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -80,8 +80,7 @@
     virtual bool needsDithering() const     { return mNeedsDithering; }
     virtual bool needsFiltering() const;
     virtual bool isSecure() const           { return mSecure; }
-    virtual bool isProtectedByApp() const   { return mProtectedByApp; }
-    virtual bool isProtectedByDRM() const   { return mProtectedByDRM; }
+    virtual bool isProtected() const;
     virtual sp<Surface> createSurface() const;
     virtual status_t ditch();
     virtual void onRemoved();
@@ -222,7 +221,6 @@
     // page-flip thread (currently main thread)
     bool mSecure;         // no screenshots
     bool mProtectedByApp; // application requires protected path to external sink
-    bool mProtectedByDRM; // DRM agent requires protected path to external sink
     Region mPostedDirtyRegion;
 
     // page-flip thread and transaction thread (currently main thread)