Enable asynchronous glReadPixels on Windows.

gpu/command_buffer/client/buffer_tracker.cc

 // Copyright (c) 2012 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/client/buffer_tracker.h"
 
 #include "gpu/command_buffer/client/cmd_buffer_helper.h"
 #include "gpu/command_buffer/client/mapped_memory.h"
 
 namespace gpu {
 namespace gles2 {
 
 BufferTracker::BufferTracker(MappedMemoryManager* manager)
     : mapped_memory_(manager) {
 }
 
 BufferTracker::~BufferTracker() {
   while (!buffers_.empty()) {
     RemoveBuffer(buffers_.begin()->first);
   }
 }
 
 BufferTracker::Buffer* BufferTracker::CreateBuffer(
-    GLuint id, GLsizeiptr size) {
+    GLuint id, GLsizeiptr size, GLsizeiptr metadata_size) {
   DCHECK_NE(0u, id);
   DCHECK_LE(0, size);
+  DCHECK_LE(0, metadata_size);
   int32 shm_id = -1;
   uint32 shm_offset = 0;
   void* address = NULL;
-  if (size)
-    address = mapped_memory_->Alloc(size, &shm_id, &shm_offset);
+  const GLsizeiptr total_size = size + metadata_size;
+  if (total_size)
+    address = mapped_memory_->Alloc(total_size, &shm_id, &shm_offset);
 
-  Buffer* buffer = new Buffer(id, size, shm_id, shm_offset, address);
+  Buffer* buffer =
+      new Buffer(id, size, shm_id, shm_offset, address, metadata_size);
   std::pair<BufferMap::iterator, bool> result =
       buffers_.insert(std::make_pair(id, buffer));
   DCHECK(result.second);
   return buffer;
 }
 
 BufferTracker::Buffer* BufferTracker::GetBuffer(GLuint client_id) {
   BufferMap::iterator it = buffers_.find(client_id);
   return it != buffers_.end() ? it->second : NULL;
 }
 
 void BufferTracker::RemoveBuffer(GLuint client_id) {
   BufferMap::iterator it = buffers_.find(client_id);
   if (it != buffers_.end()) {
     Buffer* buffer = it->second;
     buffers_.erase(it);
     if (buffer->address_)
       mapped_memory_->Free(buffer->address_);
     delete buffer;
   }
 }
 
 void BufferTracker::FreePendingToken(Buffer* buffer, int32 token) {
   if (buffer->address_)
     mapped_memory_->FreePendingToken(buffer->address_, token);
   buffer->size_ = 0;
   buffer->shm_id_ = 0;
   buffer->shm_offset_ = 0;
   buffer->address_ = NULL;
+  buffer->metadata_size_ = 0;
   buffer->last_usage_token_ = 0;
   buffer->last_async_upload_token_ = 0;
 }
 
 void BufferTracker::Unmanage(Buffer* buffer) {
   buffer->size_ = 0;
   buffer->shm_id_ = 0;
   buffer->shm_offset_ = 0;
   buffer->address_ = NULL;
+  buffer->metadata_size_ = 0;
   buffer->last_usage_token_ = 0;
   buffer->last_async_upload_token_ = 0;
 }
 
 void BufferTracker::Free(Buffer* buffer) {
   if (buffer->address_)
     mapped_memory_->Free(buffer->address_);
 
   buffer->size_ = 0;
   buffer->shm_id_ = 0;
   buffer->shm_offset_ = 0;
   buffer->address_ = NULL;
+  buffer->metadata_size_ = 0;
   buffer->last_usage_token_ = 0;
   buffer->last_async_upload_token_ = 0;
 }
 
 }  // namespace gles2
 }  // namespace gpu