VideoCaptureDeviceLinux: Add support for SPLANE+DMABUF V4L2 type capture

media/video/capture/fake_video_capture_device_unittest.cc

Index: media/video/capture/fake_video_capture_device_unittest.cc
diff --git a/media/video/capture/fake_video_capture_device_unittest.cc b/media/video/capture/fake_video_capture_device_unittest.cc
index 8890454f366eee76f06404837674b991665d265e..8d7c96ac339692574d366548101564cb93ba6532 100644
--- a/media/video/capture/fake_video_capture_device_unittest.cc
+++ b/media/video/capture/fake_video_capture_device_unittest.cc
@@ -42,6 +42,9 @@ class MockBuffer : public VideoCaptureDevice::Client::Buffer {
   gfx::GpuMemoryBufferType GetType() override {
     return gfx::SHARED_MEMORY_BUFFER;
   }
+  base::PlatformFile AsPlatformFile() const override {
+    return base::PlatformFile();
+  }
   ClientBuffer AsClientBuffer() override { return nullptr; }
 
  private: