Change Vaapi::SubmitBuffer() to accept a const buffer.

Previously we were casting away const at call sites because vaCreateBuffer
accepts a non-const buffer. However its documentation says that the data
will be copied out, and the implementation does so as well.
We can avoid this by mapping server-side memory via vaMapBuffer and copying
it ourselves, as VaapiWrapper::SubmitVAEncMiscParamBuffer does.

Bug: 844303
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: I4d66d0d6ee5e672d22a5dbe4073244515fa1b14d
Reviewed-on: https://chromium-review.googlesource.com/1080495
Commit-Queue: Sharif Elcott <selcott@chromium.org>
Reviewed-by: Pawel Osciak <posciak@chromium.org>
Cr-Commit-Position: refs/heads/master@{#564878}

media/gpu/vaapi/vaapi_h264_accelerator.cc

@@ -282,10 +282,7 @@ bool VaapiH264Accelerator::SubmitSlice(const H264PPS* pps,
                                     sizeof(slice_param), &slice_param))
     return false;
 
-  // Can't help it, blame libva...
-  void* non_const_ptr = const_cast<uint8_t*>(data);
-  return vaapi_wrapper_->SubmitBuffer(VASliceDataBufferType, size,
-                                      non_const_ptr);
+  return vaapi_wrapper_->SubmitBuffer(VASliceDataBufferType, size, data);
 }
 
 bool VaapiH264Accelerator::SubmitDecode(const scoped_refptr<H264Picture>& pic) {

media/gpu/vaapi/vaapi_video_encode_accelerator.cc

@@ -382,11 +382,8 @@ void VaapiVideoEncodeAccelerator::SubmitVAEncMiscParamBuffer(
 void VaapiVideoEncodeAccelerator::SubmitH264BitstreamBuffer(
     scoped_refptr<H264BitstreamBuffer> buffer) {
   DCHECK(encoder_thread_task_runner_->BelongsToCurrentThread());
-  // TODO(crbug.com/844303): use vaMapBuffer in VaapiWrapper::SubmitBuffer()
-  // instead to avoid this.
-  void* non_const_ptr = const_cast<uint8_t*>(buffer->data());
   if (!vaapi_wrapper_->SubmitBuffer(VAEncPackedHeaderDataBufferType,
-                                    buffer->BytesInBuffer(), non_const_ptr)) {
+                                    buffer->BytesInBuffer(), buffer->data())) {
     NOTIFY_ERROR(kPlatformFailureError, "Failed submitting a bitstream buffer");
   }
 }

media/gpu/vaapi/vaapi_vp8_accelerator.cc

@@ -216,9 +216,8 @@ bool VaapiVP8Accelerator::SubmitDecode(
                                     &slice_param))
     return false;
 
-  void* non_const_ptr = const_cast<uint8_t*>(frame_hdr->data);
   if (!vaapi_wrapper_->SubmitBuffer(VASliceDataBufferType,
-                                    frame_hdr->frame_size, non_const_ptr))
+                                    frame_hdr->frame_size, frame_hdr->data))
     return false;
 
   return vaapi_dec_->DecodeVASurface(pic->AsVaapiVP8Picture()->va_surface());

media/gpu/vaapi/vaapi_vp9_accelerator.cc

@@ -154,9 +154,8 @@ bool VaapiVP9Accelerator::SubmitDecode(
                                     sizeof(slice_param), &slice_param))
     return false;
 
-  void* non_const_ptr = const_cast<uint8_t*>(frame_hdr->data);
   if (!vaapi_wrapper_->SubmitBuffer(VASliceDataBufferType,
-                                    frame_hdr->frame_size, non_const_ptr))
+                                    frame_hdr->frame_size, frame_hdr->data))
     return false;
 
   return vaapi_dec_->DecodeVASurface(pic->AsVaapiVP9Picture()->va_surface());

media/gpu/vaapi/vaapi_wrapper.cc

@@ -909,14 +909,30 @@ scoped_refptr<VASurface> VaapiWrapper::CreateVASurfaceForPixmap(
 
 bool VaapiWrapper::SubmitBuffer(VABufferType va_buffer_type,
                                 size_t size,
-                                void* buffer) {
+                                const void* buffer) {
   base::AutoLock auto_lock(*va_lock_);
 
   VABufferID buffer_id;
   VAStatus va_res = vaCreateBuffer(va_display_, va_context_id_, va_buffer_type,
-                                   size, 1, buffer, &buffer_id);
+                                   size, 1, nullptr, &buffer_id);
   VA_SUCCESS_OR_RETURN(va_res, "Failed to create a VA buffer", false);
 
+  void* va_buffer_data = nullptr;
+  va_res = vaMapBuffer(va_display_, buffer_id, &va_buffer_data);
+  VA_LOG_ON_ERROR(va_res, "vaMapBuffer failed");
+  if (va_res != VA_STATUS_SUCCESS) {
+    vaDestroyBuffer(va_display_, buffer_id);
+    return false;
+  }
+
+  DCHECK(va_buffer_data);
+  // TODO(selcott): Investigate potentially faster alternatives to memcpy here
+  // such as libyuv::CopyX and family.
+  memcpy(va_buffer_data, buffer, size);
+
+  va_res = vaUnmapBuffer(va_display_, buffer_id);
+  VA_LOG_ON_ERROR(va_res, "vaUnmapBuffer failed");
+
   switch (va_buffer_type) {
     case VASliceParameterBufferType:
     case VASliceDataBufferType:

media/gpu/vaapi/vaapi_wrapper.h

@@ -122,7 +122,9 @@ class MEDIA_GPU_EXPORT VaapiWrapper
   // Data submitted via this method awaits in the HW codec until
   // ExecuteAndDestroyPendingBuffers() is called to execute or
   // DestroyPendingBuffers() is used to cancel a pending job.
-  bool SubmitBuffer(VABufferType va_buffer_type, size_t size, void* buffer);
+  bool SubmitBuffer(VABufferType va_buffer_type,
+                    size_t size,
+                    const void* buffer);
 
   // Submit a VAEncMiscParameterBuffer of given |misc_param_type|, copying its
   // data from |buffer| of size |size|, into HW codec. The data in |buffer| is