Add glClientWaitSync to GPU command buffer.

gpu/command_buffer/service/gles2_cmd_validation_implementation_autogen.h

Index: gpu/command_buffer/service/gles2_cmd_validation_implementation_autogen.h
diff --git a/gpu/command_buffer/service/gles2_cmd_validation_implementation_autogen.h b/gpu/command_buffer/service/gles2_cmd_validation_implementation_autogen.h
index 97c3cdd5b05b6e3eafbd632c7823353da1799c87..68df541127a94a0e920ec016e3e4a3cbca3f86a9 100644
--- a/gpu/command_buffer/service/gles2_cmd_validation_implementation_autogen.h
+++ b/gpu/command_buffer/service/gles2_cmd_validation_implementation_autogen.h
@@ -457,6 +457,11 @@ static const GLenum valid_subscription_target_table[] = {
     GL_MOUSE_POSITION_CHROMIUM,
 };
 
+static const GLbitfield valid_sync_flush_flags_table[] = {
+    GL_SYNC_FLUSH_COMMANDS_BIT,
+    0,
+};
+
 static const GLenum valid_texture_3_d_target_table[] = {
     GL_TEXTURE_3D,
     GL_TEXTURE_2D_ARRAY,
@@ -688,6 +693,8 @@ Validators::Validators()
       string_type(valid_string_type_table, arraysize(valid_string_type_table)),
       subscription_target(valid_subscription_target_table,
                           arraysize(valid_subscription_target_table)),
+      sync_flush_flags(valid_sync_flush_flags_table,
+                       arraysize(valid_sync_flush_flags_table)),
       texture_3_d_target(valid_texture_3_d_target_table,
                          arraysize(valid_texture_3_d_target_table)),
       texture_bind_target(valid_texture_bind_target_table,