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/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 7b19a4c..a9fa1ef 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -2169,6 +2169,19 @@
     if (UNLIKELY(uint32_t(dpy) >= DISPLAY_COUNT))
         return BAD_VALUE;
 
+    // make sure none of the layers are protected
+    const Vector< sp<LayerBase> >& layers(mVisibleLayersSortedByZ);
+    const size_t count = layers.size();
+    for (size_t i=0 ; i<count ; ++i) {
+        const sp<LayerBase>& layer(layers[i]);
+        const uint32_t z = layer->drawingState().z;
+        if (z >= minLayerZ && z <= maxLayerZ) {
+            if (layer->isProtected()) {
+                return INVALID_OPERATION;
+            }
+        }
+    }
+
     if (!GLExtensions::getInstance().haveFramebufferObject())
         return INVALID_OPERATION;
 
@@ -2217,8 +2230,6 @@
         glClearColor(0,0,0,1);
         glClear(GL_COLOR_BUFFER_BIT);
 
-        const Vector< sp<LayerBase> >& layers(mVisibleLayersSortedByZ);
-        const size_t count = layers.size();
         for (size_t i=0 ; i<count ; ++i) {
             const sp<LayerBase>& layer(layers[i]);
             const uint32_t z = layer->drawingState().z;