[SalesForce] Give permission to a user and profile to edit visual force page and apex class

As @Mike Chale mentions above, this can be done using the beforeunload JavaScript event handler (which fires when you are trying to leave the page). If is often easiest to leverage a framework like jQuery to make the actual implementation as simple as possible on your end, but the most basic version of it would look like the following:

jQuery(window).on('beforeunload', function()
{
  return 'Leaving this page will lose your changes. Are you sure?';
}

This would prompt the user, who would then be given the option of leaving the page or canceling to stay on the page.

I had to implement this a while ago, and wrote a blog post on some of the more intricate parts (determining when you allow the user to leave a page -- typically on submit).

http://michaelwelburn.com/2013/04/08/confirming-a-user-really-wants-to-leave-a-visualforce-page/

Problem

First of all, I don't think you need to use "Account" object or any other standard object for this requirement. You should go for the custom object, which in your case is, "Page_Views__c". And it should have at least these two fields:

1. LastViewedBy (lookup to User)
2. Count (Numeric, displaying the number of times this user has visited this page)

Logic

When a user is navigating to this VF page, you should check two things:

1. If user record is not present in the pageview object, then INSERT record with user-lookup and count (1).
2. If user record is present, then UPDATE with Count = +1

VF Page

<apex:page standardController="Page_Views__c" action="{!TotalRecordUpdate}" extensions="Displaypage" >
   <apex:form id="PageCount">
      <apex:actionFunction name="updateCount" action="{!updateCount}" reRender="PageCount" />
      Current user: {! $User.UserName } <br/>
      Page Count: {!ViewCount}
   </apex:form>
</apex:page>

Controller

public class DisplayPage {   
   public Decimal ViewCount {get; set;}

    public DisplayPage(ApexPages.StandardController Controller) {
        this.ViewCount = 0;
        //TotalRecordUpdate();  // no need to call dml or dml function in constructor
    }

    public void TotalRecordUpdate(){
        Id userid = UserInfo.getUserId();
        List<Page_View__c> pageViews = [SELECT Last_Viewed_By__c, Page_view_count__c FROM Page_View__c WHERE  Last_Viewed_By__c = : userid ];
   // system.debug(AddsName_c__c);
   if (pageViews.size() > 0 ){
       // record present, use Update
       ViewCount = pageViews[0].Page_view_Count__c +1;
       pageViews[0].Page_view_count__c = ViewCount;
       Update pageViews[0];
   }
        else{
            // record not present, Insert
            Page_View__c pv = new Page_View__c();
            pv.LastViewedBy = userid;
            ViewCount = 1;
            pv.Count__c = ViewCount;

            Insert pv;
            ViewCount = 1;
        }

    }
}

P.S. I have not tested the code above, just on-the-fly, so test it please.