Add support for GL_CHROMIUM_pixel_transfer_buffer_object.

gpu/command_buffer/client/buffer_tracker.cc

Index: gpu/command_buffer/client/buffer_tracker.cc
diff --git a/gpu/command_buffer/client/buffer_tracker.cc b/gpu/command_buffer/client/buffer_tracker.cc
new file mode 100644
index 0000000000000000000000000000000000000000..75e34115c1cb32190957ad5b401bff3fd61f36e1
--- /dev/null
+++ b/gpu/command_buffer/client/buffer_tracker.cc
@@ -0,0 +1,58 @@
+// 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 "../client/buffer_tracker.h"
+
+#include "../client/atomicops.h"
+#include "../client/cmd_buffer_helper.h"
+#include "../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) {
+  GPU_DCHECK_NE(0u, id);
+  GPU_DCHECK_LT(0u, size);
+  int32 shm_id;
+  uint32 shm_offset;
+  void* address = mapped_memory_->Alloc(size, &shm_id, &shm_offset);
+  if (!address) {
+    return NULL;
+  }
+
+  Buffer* buffer = new Buffer(id, shm_id, shm_offset, address);
+  std::pair<BufferMap::iterator, bool> result =
+      buffers_.insert(std::make_pair(id, buffer));
+  GPU_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);
+    mapped_memory_->Free(buffer->address());
+    delete buffer;
+  }
+}
+
+}  // namespace gles2
+}  // namespace gpu