Fix double-deletion of VR Shell when exiting webVR in onPause.

chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.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;
 
 import android.app.Activity;
 import android.app.PendingIntent;
 import android.content.ComponentName;
 import android.content.Intent;
@@ skipping 282 matching lines @@
         // non-VR recents, and we don't want ChromeTabbedActivity disappearing, exit VR.
         exitVRIfNecessary(false);
     }
 
     /**
      * Exits the current VR mode (WebVR or VRShell)
      * @return Whether or not we exited VR.
      */
     public boolean exitVRIfNecessary(boolean returnTo2D) {
         if (!mInVr) return false;
-        // If WebVR is presenting instruct it to exit.
-        nativeExitWebVRIfNecessary(mNativeVrShellDelegate);
         shutdownVR(returnTo2D);
         return true;
     }
 
     public void onExitVRResult(int resultCode) {
         if (resultCode == Activity.RESULT_OK) {
             mVrDaydreamApi.setVrModeEnabled(false);
         } else {
             // For now, we don't handle re-entering VR when exit fails, so keep trying to exit.
             mVrDaydreamApi.exitFromVr(EXIT_VR_RESULT, new Intent());
@@ skipping 216 matching lines @@
 
     /**
      * @return Pointer to the native VrShellDelegate object.
      */
     @CalledByNative
     private long getNativePointer() {
         return mNativeVrShellDelegate;
     }
 
     private native long nativeInit();
-    private native void nativeExitWebVRIfNecessary(long nativeVrShellDelegate);
 }