SurfaceFlinger: Fix PTS on stale buffers

SurfaceFlinger's (Layer's) shadow copy of the BufferQueue queue was
getting out of sync for a few reasons. This change fixes these by
doing the following:

- Adds a check to re-synchronize the shadow copy every time we
  successfully acquire a buffer by first dropping stale buffers before
  removing the current buffer.
- Avoids trying to perform updates for buffers which have been rejected
  (for incorrect dimensions) by SurfaceFlinger.
- Adds IGraphicBufferConsumer::setShadowQueueSize, which allows the
  consumer to notify the BufferQueue that it is maintaining a shadow
  copy of the queue and prevents it from dropping so many buffers
  during acquireBuffer that it ends up returning a buffer for which the
  consumer has not yet received an onFrameAvailable call.

Bug: 20096136
Change-Id: I78d0738428005fc19b3be85cc8f1db498043612f
(cherry picked from commit 2e36f2283f48ab764b496490c73a132acf21df3a)

1 files changed, 7 insertions, 0 deletions

diff --git a/include/gui/BufferQueueCore.h b/include/gui/BufferQueueCore.h
index e3624b7..a22015c 100644
--- a/include/gui/BufferQueueCore.h
+++ b/include/gui/BufferQueueCore.h
@@ -274,6 +274,13 @@ private:
     // mBufferAge tracks the age of the contents of the most recently dequeued
     // buffer as the number of frames that have elapsed since it was last queued
     uint64_t mBufferAge;
+
+    // mConsumerHasShadowQueue determines if acquireBuffer should be more
+    // cautious about dropping buffers so that it always returns a buffer that
+    // is represented in the consumer's shadow queue.
+    bool mConsumerHasShadowQueue;
+    size_t mConsumerShadowQueueSize;
+
 }; // class BufferQueueCore
 
 } // namespace android