Support external buffer import in VDA interface and add a V4L2SVDA impl.

content/common/gpu/media/v4l2_video_decode_accelerator.cc

Index: content/common/gpu/media/v4l2_video_decode_accelerator.cc
diff --git a/content/common/gpu/media/v4l2_video_decode_accelerator.cc b/content/common/gpu/media/v4l2_video_decode_accelerator.cc
index 3deddf07105a6aefae69a934681d3d9e8752cc0c..57a579dd9e08c1e32598f817fb413e16d1d48bbf 100644
--- a/content/common/gpu/media/v4l2_video_decode_accelerator.cc
+++ b/content/common/gpu/media/v4l2_video_decode_accelerator.cc
@@ -215,6 +215,11 @@ bool V4L2VideoDecodeAccelerator::Initialize(const Config& config,
     return false;
   }
 
+  if (config.output_mode != Config::OutputMode::ALLOCATE) {
+    NOTREACHED() << "Only ALLOCATE OutputMode is supported by this VDA";
+    return false;
+  }
+
   if (!device_->SupportsDecodeProfileForV4L2PixelFormats(
           config.profile, arraysize(supported_input_fourccs_),
           supported_input_fourccs_)) {
@@ -374,13 +379,21 @@ void V4L2VideoDecodeAccelerator::AssignPictureBuffers(
     DCHECK_EQ(output_record.picture_id, -1);
     DCHECK_EQ(output_record.cleared, false);
 
+    std::vector<base::ScopedFD> dmabuf_fds;
+    dmabuf_fds = device_->GetDmabufsForV4L2Buffer(
+        i, output_planes_count_, V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE);
+    if (dmabuf_fds.empty()) {
+      NOTIFY_ERROR(PLATFORM_FAILURE);
+      return;
+    }
+
     EGLImageKHR egl_image = device_->CreateEGLImage(egl_display_,
                                                     gl_context->GetHandle(),
                                                     buffers[i].texture_id(),
                                                     coded_size_,
                                                     i,
                                                     output_format_fourcc_,
-                                                    output_planes_count_);
+                                                    dmabuf_fds);
     if (egl_image == EGL_NO_IMAGE_KHR) {
       LOG(ERROR) << "AssignPictureBuffers(): could not create EGLImageKHR";
       // Ownership of EGLImages allocated in previous iterations of this loop