Remove Sync GetPose VRService call, implement VRVSyncProvider

chrome/android/java/src/org/chromium/chrome/browser/vr_shell/NonPresentingGvrContext.java

 // 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.
 
 package org.chromium.chrome.browser.vr_shell;
 
 /**
  * Abstracts away the NonPresentingGvrContext class, which may or may not be present at runtime
  * depending on compile flags.
  */
 public interface NonPresentingGvrContext {
     /**
      * Returns the native gvr context.
      */
     long getNativeGvrContext();
 
     /**
-     * Must be called when activity resumes.
-     */
-    void resume();
-
-    /**
-     * Must be called when activity pauses.
-     */
-    void pause();
-
-    /**
      * Shutdown the native gvr context.
      */
     void shutdown();
 }