BufferQueue: track buffer-queue by instance vs. by reference

Instead of representing the buffer-queue as a vector of buffer
indices, represent them as a vector of BufferItems (copies).
This allows modifying the buffer slots independent of the queued
buffers.

As part of this change, BufferSlot properties that are only
been relevant in the buffer-queue have been removed.

Also, invalid scalingMode in queueBuffer now returns an error.

ConsumerBase has also changed to allow reuse of the same
buffer slots by different buffers.

Change-Id: If2a698fa142b67c69ad41b8eaca6e127eb3ef75b
Signed-off-by: Lajos Molnar <lajos@google.com>
Related-to-bug: 7093648
diff --git a/services/surfaceflinger/SurfaceFlingerConsumer.cpp b/services/surfaceflinger/SurfaceFlingerConsumer.cpp
index 2869250..6912dc0 100644
--- a/services/surfaceflinger/SurfaceFlingerConsumer.cpp
+++ b/services/surfaceflinger/SurfaceFlingerConsumer.cpp
@@ -69,7 +69,7 @@
     // reject buffers which have the wrong size
     int buf = item.mBuf;
     if (rejecter && rejecter->reject(mSlots[buf].mGraphicBuffer, item)) {
-        releaseBufferLocked(buf, EGL_NO_SYNC_KHR);
+        releaseBufferLocked(buf, item.mGraphicBuffer, EGL_NO_SYNC_KHR);
         return NO_ERROR;
     }