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

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

Index: chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java b/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java
index 7841650f713c61d23b87a166788b47818b07b1fd..bea4861e16ca4a7407a987c0709897a0757c474d 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java
@@ -300,8 +300,6 @@ public class VrShellDelegate {
      */
     public boolean exitVRIfNecessary(boolean returnTo2D) {
         if (!mInVr) return false;
-        // If WebVR is presenting instruct it to exit.
-        nativeExitWebVRIfNecessary(mNativeVrShellDelegate);
         shutdownVR(returnTo2D);
         return true;
     }
@@ -538,5 +536,4 @@ public class VrShellDelegate {
     }
 
     private native long nativeInit();
-    private native void nativeExitWebVRIfNecessary(long nativeVrShellDelegate);
 }