gui: Add tests for IGraphicBufferProducer

* Basic tests only. Needs more complicated queue/dequeue tests.
* Also needs consumer-side tests to really be thorough.

Change-Id: I1099dd56d65b6e9dfa15377726d6054ce657c0ca
diff --git a/include/gui/BufferQueue.h b/include/gui/BufferQueue.h
index cab7e86..15dc645 100644
--- a/include/gui/BufferQueue.h
+++ b/include/gui/BufferQueue.h
@@ -107,7 +107,7 @@
     //
     // This will fail if the producer has dequeued any buffers, or if
     // bufferCount is invalid.  bufferCount must generally be a value
-    // between the minimum undequeued buffer count and NUM_BUFFER_SLOTS
+    // between the minimum undequeued buffer count (exclusive) and NUM_BUFFER_SLOTS
     // (inclusive).  It may also be set to zero (the default) to indicate
     // that the producer does not wish to set a value.  The minimum value
     // can be obtained by calling query(NATIVE_WINDOW_MIN_UNDEQUEUED_BUFFERS,