[Sync] Removing complexity around PROXY_TABS now that empty sessions are provided when disabled.

chrome/test/data/webui/md_history/history_metrics_test.js

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 cr.define('md_history.history_metrics_test', function() {
   /**
    * @constructor
    * @extends {md_history.BrowserService}
    */
   var TestMetricsBrowserService = function() {
@@ skipping 157 matching lines @@
                 [createWindow(['http://www.google.com', 'http://example.com'])]
             ),
             createSession(
                 'Nexus 6',
                 [
                   createWindow(['http://test.com']),
                   createWindow(['http://www.gmail.com', 'http://badssl.com'])
                 ]
             ),
           ];
-          setForeignSessions(sessionList, true);
+          setForeignSessions(sessionList);
           return PolymerTest.flushTasks();
         }).then(() => {
           assertEquals(1, histogram[SyncedTabsHistogram.HAS_FOREIGN_DATA]);
           return PolymerTest.flushTasks();
         }).then(() => {
           cards = polymerSelectAll(
               app.$$('#synced-devices'), 'history-synced-device-card');
           MockInteractions.tap(cards[0].$['card-heading']);
           assertEquals(1, histogram[SyncedTabsHistogram.COLLAPSE_SESSION]);
           MockInteractions.tap(cards[0].$['card-heading']);
@@ skipping 11 matching lines @@
               app.$$('#synced-devices').$$('#menuDeleteButton'));
           assertEquals(1, histogram[SyncedTabsHistogram.HIDE_FOR_NOW]);
         });
       });
     });
   }
   return {
     registerTests: registerTests
   };
 });