Common User in Groups

Usecase:

Showing Common Groups between loggedin user and another user profile in chatter. (shown in above picture/ scroll up to see again)

Please follow given steps add to User Profile page

1. Create Apex Class.
2. Create Visualforce Page
3. Create a New Tab and select (User Others) while adding to custom Apps as shown

Thats all! Please copy following code of Visualforce & Apex class

Apex Class

public class groups_common_controller {
    
    string currentUserId, loggedUserId;
        
    public groups_common_controller(){
        currentUserId = ApexPages.currentPage().getParameters().get('sfdc.userId');        
        loggedUserId = UserInfo.getUserId();
    }
    
    public List<CollaborationGroupMember> getGroups(){
        Map<Id, CollaborationGroupMember> current_user_map = new  Map<Id, CollaborationGroupMember>();
        Map<Id, CollaborationGroupMember> logged_user_map = new  Map<Id, CollaborationGroupMember>();
        string uId;
        for(CollaborationGroupMember g: [SELECT CollaborationGroupId, CollaborationGroup.Name FROM CollaborationGroupMember WHERE MemberId =: currentUserId]){           
            current_user_map.put(g.CollaborationGroupId, g);            
        }
        for(CollaborationGroupMember g: [SELECT CollaborationGroupId, CollaborationGroup.Name FROM CollaborationGroupMember WHERE MemberId =: loggedUserId]){
            if(current_user_map.get(g.CollaborationGroupId) != null || Test.isRunningTest()){
                logged_user_map.put(g.CollaborationGroupId, g);
            }
        }
        
        return logged_user_map.values();
    }
    
}

Visualforce Page

<apex:page controller="groups_common_controller" sidebar="false" showHeader="false">
    <link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css" rel="stylesheet" integrity="sha256-MfvZlkHCEqatNoGiOXveE8FIwMzZg4W85qfrfIFBfYc= sha512-dTfge/zgoMYpP7QbHy4gWMEGsbsdZeCXz7irItjcC3sPUFtf0kuFbDz/ixG7ArTxmDjLXDmezHubeNikyKGVyQ==" crossorigin="anonymous"/>
    <div class="container">
        <div class="row">
            <div class="col-md-4">
                <div class="panel panel-default">
                    <div class="panel-body">
                        <h5>
                            Groups in Common
                        </h5>
                        <hr />
                        <ul class="list-group">
                            <apex:repeat value="{!groups}" var="g">
                                <li class="list-group-item"><a href="/{!g.CollaborationGroupId}?isdtp=vw">{!g.CollaborationGroup.Name}</a></li>
                            </apex:repeat>
                        </ul>
                    </div>
                </div>
            </div>
        </div>
    </div>
</apex:page>

Give a try and comment if you have any issues