Release output buffer when dropping frame in HardwareVideoDecoder.

Bug: webrtc:9128
Change-Id: I0952367f74eea4603b74d822dc13b231bcba5ff6
Reviewed-on: https://webrtc-review.googlesource.com/68520
Commit-Queue: Sami Kalliomäki <sakal@webrtc.org>
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24227}

sdk/android/src/java/org/webrtc/HardwareVideoDecoder.java

@@ -423,6 +423,7 @@ class HardwareVideoDecoder implements VideoDecoder, VideoSink {
 
     synchronized (renderedTextureMetadataLock) {
       if (renderedTextureMetadata != null) {
+        codec.releaseOutputBuffer(index, false);
         return; // We are still waiting for texture for the previous frame, drop this one.
       }
       surfaceTextureHelper.setTextureSize(width, height);

sdk/android/tests/src/org/webrtc/HardwareVideoDecoderTest.java

@@ -324,7 +324,6 @@ public class HardwareVideoDecoderTest {
   }
 
   @Test
-  @Ignore("TODO(webrtc:9128): Fix")
   public void testSurfaceTextureStall_FramesDropped() throws InterruptedException {
     final int numFrames = 10;
     // Maximum number of frame the decoder can keep queued on the output side.