Update HWVideoEncoder to reuse codec buffer instead of copying the data.

In practice, this is safe since WebRTC doesn't access the buffer after the
callback returns. This avoids unnecessary memory allocations causing out of
memory errors.

Bug: b/72675429
Change-Id: I2ed0224f40b7e1fa67c7aba625b99211f9c1e0a3
Reviewed-on: https://webrtc-review.googlesource.com/49162
Commit-Queue: Sami Kalliomäki <sakal@webrtc.org>
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21932}

sdk/android/instrumentationtests/src/org/webrtc/HardwareVideoEncoderTest.java

@@ -87,7 +87,22 @@ public class HardwareVideoEncoderTest {
     public void onEncodedFrame(EncodedImage frame, VideoEncoder.CodecSpecificInfo info) {
       assertNotNull(frame);
       assertNotNull(info);
-      frameQueue.offer(frame);
+
+      // Make a copy because keeping a reference to the buffer is not allowed.
+      final ByteBuffer bufferCopy = ByteBuffer.allocateDirect(frame.buffer.remaining());
+      bufferCopy.put(frame.buffer);
+      bufferCopy.rewind();
+
+      frameQueue.offer(EncodedImage.builder()
+                           .setBuffer(bufferCopy)
+                           .setEncodedWidth(frame.encodedWidth)
+                           .setEncodedHeight(frame.encodedHeight)
+                           .setCaptureTimeNs(frame.captureTimeNs)
+                           .setFrameType(frame.frameType)
+                           .setRotation(frame.rotation)
+                           .setCompleteFrame(frame.completeFrame)
+                           .setQp(frame.qp)
+                           .createEncodedImage());
     }
 
     public EncodedImage poll() {