title: Ag grid - processCellCallback for export data does not work Angularjs
body: <p>I am using <code>ag-grid</code> for data grid in <code>Angularjs</code> application but it does not work. It does not even throw any error. Below is my export function - </p>
  
  <pre><code>exportData: function() {
          var vm = this;
          var params = {
              fileName : vm.pageTitle + '.csv',
              processCellCallback : function(params) { 
              console.log(params.value);
               if (params.value &amp;&amp; params.value.toUpperCase) {
                      return params.value.toUpperCase();
                  } else {
                      return params.value;
                  }
              }
          };
          vm.gridOptions.api.exportDataAsCsv(params);     
      }
  </code></pre>
  
  <p>Below are the versions I am using -</p>
  
  <p>Angular : 1.5.0</p>
  
  <p>Ag-grid : 2.3.5</p>
  
  <p>Thanks in advance for any help.</p>