Allow "opaque" flag to be updated

Moves the "opaque layer" from Layer to Layer::State.  This allows
it to be updated as part of a transaction.

Bug 12387406

Change-Id: I0a114ce6adf77cd12fb08f96e0691b76c475768d
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index af31852..40ca8eb 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -1380,7 +1380,7 @@
 
         // handle hidden surfaces by setting the visible region to empty
         if (CC_LIKELY(layer->isVisible())) {
-            const bool translucent = !layer->isOpaque();
+            const bool translucent = !layer->isOpaque(s);
             Rect bounds(s.transform.transform(layer->computeBounds()));
             visibleRegion.set(bounds);
             if (!visibleRegion.isEmpty()) {
@@ -1629,7 +1629,7 @@
                         const Layer::State& state(layer->getDrawingState());
                         if ((cur->getHints() & HWC_HINT_CLEAR_FB)
                                 && i
-                                && layer->isOpaque() && (state.alpha == 0xFF)
+                                && layer->isOpaque(state) && (state.alpha == 0xFF)
                                 && hasGlesComposition) {
                             // never clear the very first layer since we're
                             // guaranteed the FB is already cleared
@@ -1873,7 +1873,9 @@
             if (layer->setTransparentRegionHint(s.transparentRegion))
                 flags |= eTraversalNeeded;
         }
-        if (what & layer_state_t::eVisibilityChanged) {
+        if ((what & layer_state_t::eVisibilityChanged) ||
+                (what & layer_state_t::eOpacityChanged)) {
+            // TODO: should we just use an eFlagsChanged for this?
             if (layer->setFlags(s.flags, s.mask))
                 flags |= eTraversalNeeded;
         }