Add support for GL_CHROMIUM_pixel_transfer_buffer_object.

gpu/command_buffer/client/gles2_implementation.h

Index: gpu/command_buffer/client/gles2_implementation.h
diff --git a/gpu/command_buffer/client/gles2_implementation.h b/gpu/command_buffer/client/gles2_implementation.h
index 47fb3b07b1356d7ba2a5ccb1aa2c8d6bffd392e8..74443c1c1b8e405465bb183149260d8dffd27a60 100644
--- a/gpu/command_buffer/client/gles2_implementation.h
+++ b/gpu/command_buffer/client/gles2_implementation.h
@@ -17,6 +17,7 @@
 #include "../common/debug_marker_manager.h"
 #include "../common/gles2_cmd_utils.h"
 #include "../common/scoped_ptr.h"
+#include "../client/buffer_tracker.h"
 #include "../client/ref_counted.h"
 #include "../client/gles2_cmd_helper.h"
 #include "../client/gles2_interface.h"
@@ -534,6 +535,9 @@ class GLES2_IMPL_EXPORT GLES2Implementation : public GLES2Interface {
   // The currently bound element array buffer.
   GLuint bound_element_array_buffer_id_;
 
+  // The currently bound pixel transfer buffer.
+  GLuint bound_pixel_unpack_transfer_buffer_id_;
+
   // GL names for the buffers used to emulate client side buffers.
   GLuint client_side_array_id_;
   GLuint client_side_element_array_id_;
@@ -578,6 +582,8 @@ class GLES2_IMPL_EXPORT GLES2Implementation : public GLES2Interface {
   scoped_ptr<QueryTracker> query_tracker_;
   QueryTracker::Query* current_query_;
 
+  scoped_ptr<BufferTracker> buffer_tracker_;
+
   ErrorMessageCallback* error_message_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(GLES2Implementation);