implement getBufferSubDataAsync prototype

gpu/command_buffer/service/gles2_cmd_decoder_passthrough_handlers.cc

 // Copyright (c) 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "gpu/command_buffer/service/gles2_cmd_decoder_passthrough.h"
 
 namespace gpu {
 namespace gles2 {
 
 // Custom Handlers
@@ skipping 351 matching lines @@
   if (*location != -1) {
     return error::kInvalidArguments;
   }
   error::Error error = DoGetAttribLocation(program, name_str.c_str(), location);
   if (error != error::kNoError) {
     return error;
   }
   return error::kNoError;
 }
 
+error::Error GLES2DecoderPassthroughImpl::HandleGetBufferSubDataAsyncCHROMIUM(
+    uint32_t immediate_data_size,
+    const volatile void* cmd_data) {
+  // XXX: how do I test this?
+
+  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;
+  }
+
+  void* ptr = nullptr;
+  error::Error error =
+      DoMapBufferRange(target, offset, size, GL_MAP_READ_BIT, &ptr);
+  if (error != error::kNoError) {
+    return error;
+  }
+  memcpy(mem, ptr, size);
+  error = DoUnmapBuffer(target);
+  if (error != error::kNoError) {
+    return error;
+  }
+
+  return error::kNoError;
+}
+
+
 error::Error GLES2DecoderPassthroughImpl::HandleGetFragDataLocation(
     uint32_t immediate_data_size,
     const volatile void* cmd_data) {
   const volatile gles2::cmds::GetFragDataLocation& c =
       *static_cast<const volatile gles2::cmds::GetFragDataLocation*>(cmd_data);
   GLuint program = static_cast<GLuint>(c.program);
   Bucket* bucket = GetBucket(c.name_bucket_id);
   if (!bucket) {
     return error::kInvalidArguments;
   }
@@ skipping 2010 matching lines @@
   }
   error::Error error = DoGetFragDataIndexEXT(program, name_str.c_str(), index);
   if (error != error::kNoError) {
     return error;
   }
   return error::kNoError;
 }
 
 }  // namespace gles2
 }  // namespace gpu