Don't dispatch vrdisplayactivate event if the page that listens for it is invisible

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 393aba6c96bf6928e16868bc8f961663ac019066..b3031ddc729210e2ea38691af70656d535508b12 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
@@ -84,6 +84,7 @@ public class VrShellDelegate {
     private boolean mRequestedWebVR;
     private long mLastVRExit;
     private boolean mListeningForWebVrActivate;
+    private boolean mListeningForWebVrActivateBeforePause;
 
     public VrShellDelegate(ChromeTabbedActivity activity) {
         mActivity = activity;
@@ -149,7 +150,7 @@ public class VrShellDelegate {
     public void enterVRFromIntent(Intent intent) {
         if (!mVrAvailable) return;
         assert isVrIntent(intent);
-        if (mListeningForWebVrActivate && !mRequestedWebVR) {
+        if (mListeningForWebVrActivateBeforePause && !mRequestedWebVR) {

[mthiesse, 2016/11/30 19:02:03]

Should add a block for if (!mListeningForWebVrActivateBeforePause &&
!mRequestedWebVR && !isVrShellEnabled()) {
  mDaydreamApi.launchVrHomescreen()
}

[bshe, 2016/11/30 19:16:28]

Agree it should be fixed. But this is a different issue in my mind. So
a separate CL would make more sense?

[mthiesse, 2016/11/30 19:31:42]

I think it's an issue that's caused by this CL, so we should fix it here. Before
this CL we had the assumption that when we we're called back from Daydream, we
had something to show in VR. That's no longer the case; there's now a good
chance that we have nothing to show when we're called back.

[bshe, 2016/11/30 22:01:09]

Discussed offline. There is another issue which results DaydreamIntent not
properly
unregistered or failed to unregister, which makes the behavior confusing. So
include the
proposed fix here.

             nativeDisplayActivate(mNativeVrShellDelegate);
             return;
         }
@@ -277,7 +278,7 @@ public class VrShellDelegate {
      */
     public void maybeResumeVR() {
         if (!mVrAvailable) return;
-        if (isVrShellEnabled() || mListeningForWebVrActivate) {
+        if (isVrShellEnabled() || mListeningForWebVrActivateBeforePause) {
             registerDaydreamIntent();
         }
         // If this is still set, it means the user backed out of the DON flow, and we won't be
@@ -323,6 +324,14 @@ public class VrShellDelegate {
         if (!mVrAvailable) return;
         unregisterDaydreamIntent();
 
+        // When the active web page has a vrdisplayactivate event handler,
+        // mListeningForWebVrActivate should be set to true, which means a vrdisplayactive event
+        // should be fired once DON flow finished. However, DON flow will pause our activity, which
+        // makes the active page becomes invisible. And the event fires before the active page
+        // becomes visible again after DON finished. So here we remember the value of
+        // mListeningForWebVrActivity before pause and use this value to decide if vrdisplayactivate
+        // event should be dispatched in enterVRFromIntent.
+        mListeningForWebVrActivateBeforePause = mListeningForWebVrActivate;
         if (mNonPresentingGvrContext != null) {
             mNonPresentingGvrContext.pause();
         }