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

 // 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 66 matching lines @@
     private VrCoreVersionChecker mVrCoreVersionChecker;
 
     private boolean mInVr;
     private int mRestoreSystemUiVisibilityFlag = -1;
     private int mRestoreOrientation = ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED;
     private long mNativeVrShellDelegate;
     private Tab mTab;
     private boolean mRequestedWebVR;
     private long mLastVRExit;
     private boolean mListeningForWebVrActivate;
+    private boolean mListeningForWebVrActivateBeforePause;
 
     public VrShellDelegate(ChromeTabbedActivity activity) {
         mActivity = activity;
 
         mVrAvailable = createVrClassesBuilder() && isVrCoreCompatible() && createVrDaydreamApi()
                 && mVrDaydreamApi.isDaydreamReadyDevice();
         if (mVrAvailable) {
             mEnterVRIntent = mVrDaydreamApi.createVrIntent(
                     new ComponentName(mActivity, VR_ACTIVITY_ALIAS));
         } else {
@@ skipping 45 matching lines @@
             return false;
         }
     }
 
     /**
      * Handle a VR intent, entering VR in the process unless we're unable to.
      */
     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;
         }
         if (enterVR()) {
             if (mRequestedWebVR) nativeSetPresentResult(mNativeVrShellDelegate, true);
         } else {
             if (mRequestedWebVR) nativeSetPresentResult(mNativeVrShellDelegate, false);
             if (!mVrDaydreamApi.exitFromVr(EXIT_VR_RESULT, new Intent())) {
                 mVrDaydreamApi.setVrModeEnabled(false);
             }
@@ skipping 107 matching lines @@
         // how VrShell was created.
         shutdownVR(true, !isVrShellEnabled());
         return true;
     }
 
     /**
      * Resumes VR Shell.
      */
     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
         // receiving an intent from daydream.
         if (mRequestedWebVR) {
             nativeSetPresentResult(mNativeVrShellDelegate, false);
             mRequestedWebVR = false;
         }
 
         // TODO(bshe): Ideally, we do not need two gvr context exist at the same time. We can
@@ skipping 25 matching lines @@
         }
     }
 
     /**
      * Pauses VR Shell.
      */
     public void maybePauseVR() {
         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();
         }
 
         // TODO(mthiesse): When VR Shell lives in its own activity, and integrates with Daydream
         // home, pause instead of exiting VR here. For now, because VR Apps shouldn't show up in the
         // non-VR recents, and we don't want ChromeTabbedActivity disappearing, exit VR.
         exitVRIfNecessary(false);
     }
 
@@ skipping 196 matching lines @@
      */
     @CalledByNative
     private long getNativePointer() {
         return mNativeVrShellDelegate;
     }
 
     private native long nativeInit();
     private native void nativeSetPresentResult(long nativeVrShellDelegate, boolean result);
     private native void nativeDisplayActivate(long nativeVrShellDelegate);
 }