Fix CleanupReferenceTest on Android M

content/public/android/javatests/src/org/chromium/content/common/CleanupReferenceTest.java

 // Copyright 2013 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.
 
 package org.chromium.content.common;
 
 import android.test.InstrumentationTestCase;
 import android.test.suitebuilder.annotation.SmallTest;
 
 import org.chromium.base.annotations.SuppressFBWarnings;
@@ skipping 33 matching lines @@
     public void setUp() throws Exception {
         super.setUp();
         sObjectCount.set(0);
     }
 
     @SuppressFBWarnings("DM_GC")
     private void collectGarbage() {
         // While this is only a 'hint' to the VM, it's generally effective and sufficient on
         // dalvik. If this changes in future, maybe try allocating a few gargantuan objects
         // too, to force the GC to work.
-        System.gc();
+        Runtime.getRuntime().gc();
     }
 
     @SuppressFBWarnings("DLS_DEAD_LOCAL_STORE")
     @SmallTest
     @Feature({"AndroidWebView"})
     public void testCreateSingle() throws Throwable {
         assertEquals(0, sObjectCount.get());
 
         ReferredObject instance = new ReferredObject();
         assertEquals(1, sObjectCount.get());
@@ skipping 33 matching lines @@
         collectGarbage();
         CriteriaHelper.pollInstrumentationThread(Criteria.equals(0, new Callable<Integer>() {
             @Override
             public Integer call() {
                 return sObjectCount.get();
             }
         }));
     }
 
 }