SurfaceFlinger: use the HWC gralloc usage bit

This change makes SurfaceFlinger always use the
GRALLOC_USAGE_HW_COMPOSER usage bit when allocating buffers that may be
passed to the HWComposer.

Change-Id: I70362a8ede2b359fb2046853f85149d597465817

include/ui/GraphicBuffer.h

@@ -62,6 +62,7 @@ public:
         USAGE_HW_TEXTURE        = GRALLOC_USAGE_HW_TEXTURE,
         USAGE_HW_RENDER         = GRALLOC_USAGE_HW_RENDER,
         USAGE_HW_2D             = GRALLOC_USAGE_HW_2D,
+        USAGE_HW_COMPOSER       = GRALLOC_USAGE_HW_COMPOSER,
         USAGE_HW_MASK           = GRALLOC_USAGE_HW_MASK
     };
 

services/surfaceflinger/Layer.cpp

@@ -559,6 +559,7 @@ uint32_t Layer::getEffectiveUsage(uint32_t usage) const
         // need a hardware-protected path to external video sink
         usage |= GraphicBuffer::USAGE_PROTECTED;
     }
+    usage |= GraphicBuffer::USAGE_HW_COMPOSER;
     return usage;
 }