Improve indexed gl state related GL commands.

gpu/command_buffer/service/indexed_buffer_binding_host.h

 // 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.
 
 #ifndef GPU_COMMAND_BUFFER_SERVICE_INDEXED_BUFFER_BINDING_HOST_H_
 #define GPU_COMMAND_BUFFER_SERVICE_INDEXED_BUFFER_BINDING_HOST_H_
 
 #include <vector>
 
 #include "base/memory/ref_counted.h"
@@ skipping 28 matching lines @@
 
   // This is called when the host become active.
   void OnBindHost(GLenum target);
 
   void RemoveBoundBuffer(Buffer* buffer);
 
   Buffer* GetBufferBinding(GLuint index) const;
   GLsizeiptr GetBufferSize(GLuint index) const;
   GLintptr GetBufferStart(GLuint index) const;
 
+  // This is used only for UNIFORM_BUFFER bindings in context switching.
+  void RestoreBindings(IndexedBufferBindingHost* prev);
+
  protected:
   friend class base::RefCounted<IndexedBufferBindingHost>;
 
   virtual ~IndexedBufferBindingHost();
 
  private:
   enum IndexedBufferBindingType {
     kBindBufferBase,
     kBindBufferRange,
     kBindBufferNone
   };
 
   struct IndexedBufferBinding {
     IndexedBufferBindingType type;
     scoped_refptr<Buffer> buffer;
 
     // The following fields are only used if |type| is kBindBufferRange.
     GLintptr offset;
     GLsizeiptr size;
     // The full buffer size at the last successful glBindBufferRange call.
     GLsizeiptr effective_full_buffer_size;
 
     IndexedBufferBinding();
     IndexedBufferBinding(const IndexedBufferBinding& other);
     ~IndexedBufferBinding();
 
+    bool operator==(const IndexedBufferBinding& other) const;
+
     void SetBindBufferBase(Buffer* _buffer);
     void SetBindBufferRange(
         Buffer* _buffer, GLintptr _offset, GLsizeiptr _size);
     void Reset();
   };
 
   // This is called on Desktop GL lower than 4.2, where the range
   // (offset + size) can't go beyond the buffer's size.
   static void DoAdjustedBindBufferRange(
       GLenum target, GLuint index, GLuint service_id, GLintptr offset,
       GLsizeiptr size, GLsizeiptr full_buffer_size);
 
+  void UpdateMaxNonNullBindingIndex(size_t changed_index);
+
   std::vector<IndexedBufferBinding> buffer_bindings_;
 
   bool needs_emulation_;
+
+  // This is used for optimization purpose in context switching.
+  size_t max_non_null_binding_index_plus_one_;
 };
 
 }  // namespace gles2
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_SERVICE_INDEXED_BUFFER_BINDING_HOST_H_