Add Viewport Display Color to the Object Info node

Viewport display Color (also called Base Color if Use Nodes is disabled) defines the color of the material in Solid view. The python thingy for it is: bpy.data.materials["Material"].diffuse_color

If the color was accessible in the node, you could use it as a sort base color for the material, so the shader could work off of it, and have the same base color display in Solid view (without having to constantly manually adjust it).

I know you can probably access the color with a driver, but this would a lot cleaner and easier to use.