media/gpu/v4l2: Polish V4L2DecodeSurface class.

This CL adds sequence check at each method, and check the release
callback is null when setting it.

Bug: 1020668
Test: run vda_tests on kevin

Change-Id: Ia2760e1a787b0ca65a652b58a4f7ecfc66b61e8a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1974720
Commit-Queue: Chih-Yu Huang <akahuang@chromium.org>
Reviewed-by: Alexandre Courbot <acourbot@chromium.org>
Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#726299}

media/gpu/v4l2/v4l2_decode_surface.cc

@@ -79,6 +79,7 @@ void V4L2DecodeSurface::SetDecodeDoneCallback(base::OnceClosure done_cb) {
 
 void V4L2DecodeSurface::SetReleaseCallback(base::OnceClosure release_cb) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+  DCHECK(!release_cb_);
 
   release_cb_ = std::move(release_cb);
 }
@@ -130,6 +131,7 @@ bool V4L2ConfigStoreDecodeSurface::Submit() {
 
 void V4L2RequestDecodeSurface::PrepareSetCtrls(
     struct v4l2_ext_controls* ctrls) const {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   DCHECK_NE(ctrls, nullptr);
   DCHECK(request_ref_.IsValid());
 
@@ -139,6 +141,7 @@ void V4L2RequestDecodeSurface::PrepareSetCtrls(
 
 void V4L2RequestDecodeSurface::PrepareQueueBuffer(
     struct v4l2_buffer* buffer) const {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   DCHECK_NE(buffer, nullptr);
   DCHECK(request_ref_.IsValid());
 
@@ -153,12 +156,15 @@ void V4L2RequestDecodeSurface::PrepareQueueBuffer(
 }
 
 uint64_t V4L2RequestDecodeSurface::GetReferenceID() const {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+
   // Convert the input buffer ID to what the internal representation of
   // the timestamp we submitted will be (tv_usec * 1000).
   return output_record() * 1000;
 }
 
 bool V4L2RequestDecodeSurface::Submit() {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   DCHECK(request_ref_.IsValid());
 
   return std::move(request_ref_).Submit().IsValid();

media/gpu/v4l2/v4l2_decode_surface.h

@@ -22,7 +22,8 @@ namespace media {
 
 // A V4L2-specific decode surface generated by V4L2DecodeSurfaceHandler.
 // It is used to store common picture metadata (e.g. visible_rect) and
-// platform-specific metadata (e.g. {input,output}_record).
+// platform-specific metadata (e.g. {input,output}_record). All the methods
+// should be called on the same sequence.
 class V4L2DecodeSurface : public base::RefCounted<V4L2DecodeSurface> {
  public:
   // V4L2DecodeSurfaceHandler maintains a list of InputRecords, which records
@@ -48,6 +49,8 @@ class V4L2DecodeSurface : public base::RefCounted<V4L2DecodeSurface> {
   // decoding into this surface is finished. The callback is reset afterwards,
   // so it needs to be set again before each decode operation.
   void SetDecodeDoneCallback(base::OnceClosure done_cb);
+  // Set the callback that will be called when the surface is released. This
+  // method must be called one time at most.
   void SetReleaseCallback(base::OnceClosure release_cb);
 
   // Update the passed v4l2_ext_controls structure to add the request or