I used Odoo 9 sharing products for multiple company.

How to set domain company_id in "ir.actions.act_window" so that every user can only see their own products. 

I also look for Record Rules, but it restrict another company's product in many2one field .

I try this but still not work.

<record id="mmg_product_template_mitra_action" model="ir.actions.act_window">
            <field name="name">Products</field>
            <field name="type">ir.actions.act_window</field>
            <field name="res_model">product.template</field>
            <field name="view_mode">kanban,tree,form</field>
            <field name="view_type">form</field>
            <field name="view_id" ref="product.product_template_kanban_view"/>
            <field name="context">{"search_default_filter_to_sell":1,"custom":1}</field>
            <field name="domain">[('company_id','=',user.company_id)]</field>
            <field name="help" type="html">
                <p class="oe_view_nocontent_create">
                    Click to define a new product.
                </p><p>
                    You must define a product for everything you sell, whether it's a physical product, a consumable or a service you offer to  customers.               
                </p><p>
                    The product form contains information to simplify the sale process: price, notes in the quotation, accounting data, procurement methods, etc.
                </p>
            </field>
        </record>