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

content/common/gpu/media/dxva_video_decode_accelerator_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/common/gpu/media/dxva_video_decode_accelerator_win.h"
 
 #include <memory>
 
 #if !defined(OS_WIN)
 #error This file should only be built on Windows.
@@ skipping 919 matching lines @@
   if (get_gl_context_cb_.is_null() || make_context_current_cb_.is_null()) {
     NOTREACHED() << "GL callbacks are required for this VDA";
     return false;
   }
 
   if (config.is_encrypted) {
     NOTREACHED() << "Encrypted streams are not supported for this VDA";
     return false;
   }
 
+  if (config.output_mode != Config::OutputMode::ALLOCATE) {
+    NOTREACHED() << "Only ALLOCATE OutputMode is supported by this VDA";
+    return false;
+  }
+
   client_ = client;
 
   main_thread_task_runner_ = base::MessageLoop::current()->task_runner();
 
   bool profile_supported = false;
   for (const auto& supported_profile : kSupportedProfiles) {
     if (config.profile == supported_profile) {
       profile_supported = true;
       break;
     }
@@ skipping 2016 matching lines @@
   DismissStaleBuffers(true);
   Invalidate();
   Initialize(config_, client_);
   decoder_thread_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&DXVAVideoDecodeAccelerator::DecodePendingInputBuffers,
                  base::Unretained(this)));
 }
 
 }  // namespace content