V4L2VEA: fix keyframe is not generated on nyan

content/common/gpu/media/v4l2_video_encode_accelerator.cc

Index: content/common/gpu/media/v4l2_video_encode_accelerator.cc
diff --git a/content/common/gpu/media/v4l2_video_encode_accelerator.cc b/content/common/gpu/media/v4l2_video_encode_accelerator.cc
index d724d8dea40fb159fd6868e52e16281a3e14f41b..4d58cd17c55ff166a1368268750f8455c5ad2d6a 100644
--- a/content/common/gpu/media/v4l2_video_encode_accelerator.cc
+++ b/content/common/gpu/media/v4l2_video_encode_accelerator.cc
@@ -360,15 +360,16 @@ void V4L2VideoEncodeAccelerator::EncodeTask(
     std::vector<struct v4l2_ext_control> ctrls;
     struct v4l2_ext_control ctrl;
     memset(&ctrl, 0, sizeof(ctrl));
-    ctrl.id = V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME;
+    // Nyan still uses the old control and it reports success for unknown
+    // controls. Try the old control first.
+    // TODO(wuchengli): remove this after http://crosbug.com/p/53598 is fixed.
+    ctrl.id = V4L2_CID_MPEG_MFC51_VIDEO_FORCE_FRAME_TYPE;
+    ctrl.value = V4L2_MPEG_MFC51_VIDEO_FORCE_FRAME_TYPE_I_FRAME;
     ctrls.push_back(ctrl);
     if (!SetExtCtrls(ctrls)) {
-      // Some platforms still use the old control. Fallback before they are
-      // updated.
       ctrls.clear();
       memset(&ctrl, 0, sizeof(ctrl));
-      ctrl.id = V4L2_CID_MPEG_MFC51_VIDEO_FORCE_FRAME_TYPE;
-      ctrl.value = V4L2_MPEG_MFC51_VIDEO_FORCE_FRAME_TYPE_I_FRAME;
+      ctrl.id = V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME;
       ctrls.push_back(ctrl);
       if (!SetExtCtrls(ctrls)) {
         LOG(ERROR) << "Failed requesting keyframe";