Notify VRDeviceProviders when there are pages listening for vrdisplayactivate

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 bea4861e16ca4a7407a987c0709897a0757c474d..13226dd440dfdf1dc1dc54db2e6defa93654dbf7 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
@@ -77,6 +77,7 @@ public class VrShellDelegate {
     private Tab mTab;
     private boolean mRequestedWebVR;
     private long mLastVRExit;
+    private boolean mListeningForWebVrActivate;
 
     public VrShellDelegate(ChromeTabbedActivity activity) {
         mActivity = activity;
@@ -366,6 +367,11 @@ public class VrShellDelegate {
         mNonPresentingGvrContext = null;
     }
 
+    @CalledByNative
+    private void setListeningForWebVrActivate(boolean listening) {
+        mListeningForWebVrActivate = listening;

[dcheng, 2016/11/17 19:08:04]

is this write-only? Will it be used in a followup?

[bajones, 2016/11/17 19:23:28]

Yes, the intent is to use it in a followup. (Needs
https://codereview.chromium.org/2510873003 to land before it can be used, IIRC)

+    }
+
     /**
      * Exits VR Shell, performing all necessary cleanup.
      */