implement getBufferSubDataAsync prototype

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index 7b7def51edd37349492a3e9cbe089be975e76bcb..454bb408466f91a4dd6240844262ed1ad939deeb 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -11793,6 +11793,58 @@ error::Error GLES2DecoderImpl::HandleGetAttribLocation(
     c.program, c.location_shm_id, c.location_shm_offset, name_str);
 }
 
+error::Error GLES2DecoderImpl::HandleGetBufferSubDataAsyncCHROMIUM(
+    uint32_t immediate_data_size,
+    const volatile void* cmd_data) {
+  if (!unsafe_es3_apis_enabled()) {
+    return error::kUnknownCommand;
+  }
+  const volatile gles2::cmds::GetBufferSubDataAsyncCHROMIUM& c =
+      *static_cast<const volatile gles2::cmds::GetBufferSubDataAsyncCHROMIUM*>(
+          cmd_data);
+  GLenum target = static_cast<GLenum>(c.target);
+  GLintptr offset = static_cast<GLintptr>(c.offset);
+  GLsizeiptr size = static_cast<GLsizeiptr>(c.size);
+  uint32_t data_shm_id = static_cast<uint32_t>(c.data_shm_id);
+
+  int8_t* mem =
+      GetSharedMemoryAs<int8_t*>(data_shm_id, c.data_shm_offset, size);
+  if (!mem) {
+    return error::kOutOfBounds;
+  }
+
+  if (!validators_->buffer_target.IsValid(target)) {
+    return error::kInvalidArguments;
+  }
+
+  Buffer* buffer = buffer_manager()->GetBufferInfoForTarget(&state_, target);
+  if (!buffer) {
+    LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION, "glGetBufferSubDataAsyncCHROMIUM",
+                       "no buffer bound to target");
+    return error::kNoError;
+  }
+  if (!buffer->CheckRange(offset, size)) {
+    LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, "glGetBufferSubDataAsyncCHROMIUM",
+                       "invalid range");
+    return error::kNoError;
+  }
+
+  LOCAL_COPY_REAL_GL_ERRORS_TO_WRAPPER("glGetBufferSubDataAsyncCHROMIUM");
+
+  void* ptr = glMapBufferRange(target, offset, size, GL_MAP_READ_BIT);
+  if (ptr == nullptr) {
+    return error::kInvalidArguments;
+  }
+  memcpy(mem, ptr, size);
+  glUnmapBuffer(target);
+
+  GLenum error = LOCAL_PEEK_GL_ERROR("glGetBufferSubDataAsyncCHROMIUM");
+  if (error != GL_NO_ERROR) {
+    return error::kInvalidArguments;
+  }
+  return error::kNoError;
+}
+
 error::Error GLES2DecoderImpl::GetUniformLocationHelper(
     GLuint client_id,
     uint32_t location_shm_id,