media: cros-codecs: factorize dummy backends

The dummy backends behave the same regardless of the codec, so factorize
their declaration as well as their implementation of VideoDecoderBackend
to avoid duplicate code.

BUG=b:214478588
TEST=cargo test --features vaapi -p cros-codecs

Change-Id: Ibaa694b885c1ccf969aed3a0cb167a254e0eaab5
Reviewed-on: https://chromium-review.googlesource.com/c/crosvm/crosvm/+/4060492
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.corp-partner.google.com>
Reviewed-by: Keiichi Watanabe <keiichiw@chromium.org>
Commit-Queue: Alexandre Courbot <acourbot@chromium.org>

media/cros-codecs/src/decoders/h264/backends/stateless/dummy.rs

@@ -6,7 +6,6 @@
 //! run so we can test it in isolation.
 
 use std::cell::RefCell;
-use std::collections::HashSet;
 use std::collections::VecDeque;
 use std::rc::Rc;
 
@@ -22,40 +21,6 @@ use crate::decoders::h264::parser::Sps;
 use crate::decoders::h264::picture::H264Picture;
 use crate::decoders::VideoDecoderBackend;
 use crate::utils::dummy::*;
-use crate::DecodedFormat;
-use crate::Resolution;
-
-pub struct Backend;
-
-impl VideoDecoderBackend for Backend {
-    fn num_resources_total(&self) -> usize {
-        1
-    }
-
-    fn num_resources_left(&self) -> usize {
-        1
-    }
-
-    fn format(&self) -> Option<DecodedFormat> {
-        None
-    }
-
-    fn try_format(&mut self, _: DecodedFormat) -> crate::decoders::Result<()> {
-        Ok(())
-    }
-
-    fn supported_formats_for_stream(&self) -> crate::decoders::Result<HashSet<DecodedFormat>> {
-        Ok(HashSet::new())
-    }
-
-    fn coded_resolution(&self) -> Option<Resolution> {
-        None
-    }
-
-    fn display_resolution(&self) -> Option<Resolution> {
-        None
-    }
-}
 
 impl StatelessDecoderBackend for Backend {
     type Handle = Handle<H264Picture<BackendHandle>>;

media/cros-codecs/src/decoders/h264/decoder.rs

@@ -2557,7 +2557,6 @@ where
 pub mod tests {
     use std::io::Cursor;
 
-    use crate::decoders::h264::backends::stateless::dummy::Backend;
     use crate::decoders::h264::decoder::Decoder;
     use crate::decoders::h264::nalu_reader::NaluReader;
     use crate::decoders::h264::parser::Nalu;
@@ -2567,6 +2566,7 @@ pub mod tests {
     use crate::decoders::DecodedHandle;
     use crate::decoders::DynDecodedHandle;
     use crate::decoders::VideoDecoder;
+    use crate::utils::dummy::Backend;
 
     pub fn process_ready_frames<Handle>(
         decoder: &mut Decoder<Handle>,

media/cros-codecs/src/decoders/vp8/backends/stateless/dummy.rs

@@ -6,7 +6,6 @@
 // run so we can test it in isolation.
 
 use std::cell::RefCell;
-use std::collections::HashSet;
 use std::collections::VecDeque;
 use std::rc::Rc;
 
@@ -14,40 +13,6 @@ use crate::decoders::vp8::backends::stateless::StatelessDecoderBackend;
 use crate::decoders::vp8::backends::stateless::Vp8Picture;
 use crate::decoders::VideoDecoderBackend;
 use crate::utils::dummy::*;
-use crate::DecodedFormat;
-use crate::Resolution;
-
-pub struct Backend;
-
-impl VideoDecoderBackend for Backend {
-    fn num_resources_total(&self) -> usize {
-        1
-    }
-
-    fn num_resources_left(&self) -> usize {
-        1
-    }
-
-    fn format(&self) -> Option<DecodedFormat> {
-        None
-    }
-
-    fn try_format(&mut self, _: DecodedFormat) -> crate::decoders::Result<()> {
-        Ok(())
-    }
-
-    fn supported_formats_for_stream(&self) -> crate::decoders::Result<HashSet<DecodedFormat>> {
-        Ok(HashSet::new())
-    }
-
-    fn coded_resolution(&self) -> Option<Resolution> {
-        None
-    }
-
-    fn display_resolution(&self) -> Option<Resolution> {
-        None
-    }
-}
 
 impl StatelessDecoderBackend for Backend {
     type Handle = Handle<Vp8Picture<BackendHandle>>;

media/cros-codecs/src/decoders/vp8/decoder.rs

@@ -462,13 +462,13 @@ pub mod tests {
 
     use bytes::Buf;
 
-    use crate::decoders::vp8::backends::stateless::dummy::Backend;
     use crate::decoders::vp8::decoder::Decoder;
     use crate::decoders::vp8::parser::Header;
     use crate::decoders::BlockingMode;
     use crate::decoders::DecodedHandle;
     use crate::decoders::DynDecodedHandle;
     use crate::decoders::VideoDecoder;
+    use crate::utils::dummy::Backend;
 
     /// Read and return the data from the next IVF packet. Returns `None` if there is no more data
     /// to read.

media/cros-codecs/src/decoders/vp9/backends/stateless/dummy.rs

@@ -6,7 +6,6 @@
 //! run so we can test it in isolation.
 
 use std::cell::RefCell;
-use std::collections::HashSet;
 use std::collections::VecDeque;
 use std::rc::Rc;
 
@@ -15,40 +14,6 @@ use crate::decoders::vp9::backends::stateless::Vp9Picture;
 use crate::decoders::vp9::parser::NUM_REF_FRAMES;
 use crate::decoders::VideoDecoderBackend;
 use crate::utils::dummy::*;
-use crate::DecodedFormat;
-use crate::Resolution;
-
-pub struct Backend;
-
-impl VideoDecoderBackend for Backend {
-    fn num_resources_total(&self) -> usize {
-        1
-    }
-
-    fn num_resources_left(&self) -> usize {
-        1
-    }
-
-    fn format(&self) -> Option<DecodedFormat> {
-        None
-    }
-
-    fn try_format(&mut self, _: DecodedFormat) -> crate::decoders::Result<()> {
-        Ok(())
-    }
-
-    fn supported_formats_for_stream(&self) -> crate::decoders::Result<HashSet<DecodedFormat>> {
-        Ok(HashSet::new())
-    }
-
-    fn coded_resolution(&self) -> Option<Resolution> {
-        None
-    }
-
-    fn display_resolution(&self) -> Option<Resolution> {
-        None
-    }
-}
 
 impl StatelessDecoderBackend for Backend {
     type Handle = Handle<Vp9Picture<BackendHandle>>;

media/cros-codecs/src/decoders/vp9/decoder.rs

@@ -440,13 +440,13 @@ pub mod tests {
 
     use bytes::Buf;
 
-    use crate::decoders::vp9::backends::stateless::dummy::Backend;
     use crate::decoders::vp9::decoder::Decoder;
     use crate::decoders::vp9::parser::Header;
     use crate::decoders::BlockingMode;
     use crate::decoders::DecodedHandle;
     use crate::decoders::DynDecodedHandle;
     use crate::decoders::VideoDecoder;
+    use crate::utils::dummy::Backend;
 
     /// Read and return the data from the next IVF packet. Returns `None` if there is no more data
     /// to read.

media/cros-codecs/src/utils/dummy.rs

@@ -6,6 +6,7 @@
 //! run so we can test it in isolation.
 
 use std::cell::RefCell;
+use std::collections::HashSet;
 use std::rc::Rc;
 
 use crate::decoders::DecodedHandle;
@@ -14,6 +15,8 @@ use crate::decoders::FrameInfo;
 use crate::decoders::MappableHandle;
 use crate::decoders::Picture;
 use crate::decoders::Result;
+use crate::decoders::VideoDecoderBackend;
+use crate::DecodedFormat;
 use crate::Resolution;
 
 pub struct BackendHandle;
@@ -64,3 +67,36 @@ impl<T: FrameInfo> DecodedHandle for Handle<Picture<T, BackendHandle>> {
 
     fn set_display_order(&mut self, _: u64) {}
 }
+
+/// Dummy backend that can be used for any codec.
+pub struct Backend;
+
+impl VideoDecoderBackend for Backend {
+    fn num_resources_total(&self) -> usize {
+        1
+    }
+
+    fn num_resources_left(&self) -> usize {
+        1
+    }
+
+    fn format(&self) -> Option<DecodedFormat> {
+        None
+    }
+
+    fn try_format(&mut self, _: DecodedFormat) -> crate::decoders::Result<()> {
+        Ok(())
+    }
+
+    fn supported_formats_for_stream(&self) -> crate::decoders::Result<HashSet<DecodedFormat>> {
+        Ok(HashSet::new())
+    }
+
+    fn coded_resolution(&self) -> Option<Resolution> {
+        None
+    }
+
+    fn display_resolution(&self) -> Option<Resolution> {
+        None
+    }
+}