Implement client side PBOs for glReadPixel

gpu/command_buffer/client/buffer_tracker.h

 // 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.
 
 #ifndef GPU_COMMAND_BUFFER_CLIENT_BUFFER_TRACKER_H_
 #define GPU_COMMAND_BUFFER_CLIENT_BUFFER_TRACKER_H_
 
 #include <GLES2/gl2.h>
 
 #include <queue>
@@ skipping 16 matching lines @@
     Buffer(GLuint id,
            unsigned int size,
            int32 shm_id,
            uint32 shm_offset,
            void* address)
         : id_(id),
           size_(size),
           shm_id_(shm_id),
           shm_offset_(shm_offset),
           address_(address),
-          mapped_(false) {
+          mapped_(false),
+          transfer_ready_token_(0) {
     }
 
     GLenum id() const {
       return id_;
     }
 
     unsigned int size() const {
       return size_;
     }
 
@@ skipping 10 matching lines @@
     }
 
     void set_mapped(bool mapped) {
       mapped_ = mapped;
     }
 
     bool mapped() const {
       return mapped_;
     }
 
+    void set_transfer_ready_token(int token) {
+      transfer_ready_token_ = token;
+    }
+
+    uint32 transfer_ready_token() const {
+      return transfer_ready_token_;
+    }
+
    private:
     friend class BufferTracker;
     friend class BufferTrackerTest;
 
     GLuint id_;
     unsigned int size_;
     int32 shm_id_;
     uint32 shm_offset_;
     void* address_;
     bool mapped_;
+    int32 transfer_ready_token_;
   };
 
   BufferTracker(MappedMemoryManager* manager);
   ~BufferTracker();
 
   Buffer* CreateBuffer(GLuint id, GLsizeiptr size);
   Buffer* GetBuffer(GLuint id);
   void RemoveBuffer(GLuint id);
 
   // Frees the block of memory associated with buffer, pending the passage
   // of a token.
   void FreePendingToken(Buffer*, int32 token);
 
  private:
   typedef gpu::hash_map<GLuint, Buffer*> BufferMap;
 
   MappedMemoryManager* mapped_memory_;
   BufferMap buffers_;
 
   DISALLOW_COPY_AND_ASSIGN(BufferTracker);
 };
 
 }  // namespace gles2
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_CLIENT_BUFFER_TRACKER_H_