BufferQueue improvements and APIs changes

this is the first step of a series of improvements to
BufferQueue. A few things happen in this change:

- setSynchronousMode() goes away as well as the SynchronousModeAllowed flag
- BufferQueue now defaults to (what used to be) synchronous mode
- a new "controlled by app" flag is passed when creating consumers and producers
  those flags are used to put the BufferQueue in a mode where it
  will never block if both flags are set. This is achieved by:
  - returning an error from dequeueBuffer() if it would block
  - making sure a buffer is always available by replacing
    the previous buffer with the new one in queueBuffer()
    (note: this is similar to what asynchrnous mode used to be)

Note: in this change EGL's swap-interval 0 is broken; this will be
fixed in another change.

Change-Id: I691f9507d6e2e158287e3039f2a79a4d4434211d
diff --git a/include/gui/BufferItemConsumer.h b/include/gui/BufferItemConsumer.h
index 0af6f8e..9370e81 100644
--- a/include/gui/BufferItemConsumer.h
+++ b/include/gui/BufferItemConsumer.h
@@ -51,9 +51,11 @@
     // the consumer usage flags passed to the graphics allocator. The
     // bufferCount parameter specifies how many buffers can be locked for user
     // access at the same time.
+    // controlledByApp tells whether this consumer is controlled by the
+    // application.
     BufferItemConsumer(const sp<BufferQueue>& bq, uint32_t consumerUsage,
             int bufferCount = BufferQueue::MIN_UNDEQUEUED_BUFFERS,
-            bool synchronousMode = false);
+            bool controlledByApp = false);
 
     virtual ~BufferItemConsumer();