Perform glReadPixels with PBOs in the gpu, if PBOs are available.

gpu/command_buffer/client/gles2_cmd_helper_autogen.h

Index: gpu/command_buffer/client/gles2_cmd_helper_autogen.h
diff --git a/gpu/command_buffer/client/gles2_cmd_helper_autogen.h b/gpu/command_buffer/client/gles2_cmd_helper_autogen.h
index a290365bcc70ed35b659175808d4830f60592e3d..9c2898e8c65171754dd7a92bff0cdc112e6f3c1e 100644
--- a/gpu/command_buffer/client/gles2_cmd_helper_autogen.h
+++ b/gpu/command_buffer/client/gles2_cmd_helper_autogen.h
@@ -923,12 +923,12 @@
   void ReadPixels(
       GLint x, GLint y, GLsizei width, GLsizei height, GLenum format,
       GLenum type, uint32 pixels_shm_id, uint32 pixels_shm_offset,
-      uint32 result_shm_id, uint32 result_shm_offset) {
+      uint32 result_shm_id, uint32 result_shm_offset, GLboolean async) {
     gles2::cmds::ReadPixels* c = GetCmdSpace<gles2::cmds::ReadPixels>();
     if (c) {
       c->Init(
           x, y, width, height, format, type, pixels_shm_id, pixels_shm_offset,
-          result_shm_id, result_shm_offset);
+          result_shm_id, result_shm_offset, async);
     }
   }