Android: Fix texture leak.

The bug fix in https://codereview.webrtc.org/2033943004 was
incomplete, and leaks the texture in the case of texture frames
arriving during close. See also the similar bug fixed in
https://codereview.webrtc.org/2012773004.

BUG=webrtc:5966
R=perkj@webrtc.org, sakal@webrtc.org

Review URL: https://codereview.webrtc.org/2044383002 .

Cr-Commit-Position: refs/heads/master@{#13067}

webrtc/api/java/jni/androidvideocapturer_jni.cc

@@ -261,6 +261,7 @@ void AndroidVideoCapturerJni::OnTextureFrame(int width,
   rtc::CritScope cs(&capturer_lock_);
   if (!capturer_) {
     LOG(LS_WARNING) << "OnTextureFrame() called for closed capturer.";
+    surface_texture_helper_->ReturnTextureFrame();
     return;
   }
   int adapted_width;