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) {
             nativeDisplayActivate(mNativeVrShellDelegate);
             return;
         }
+        // Normally, if the active page doesn't have a vrdisplayactivate listener, and WebVR was not
+        // presenting and VrShell was not enabled, we shouldn't enter VR and Daydream Homescreen
+        // should show after DON flow. But due to a failure in unregisterDaydreamIntent, we still
+        // try to enterVR. Here we detect this case and force switch to Daydream Homescreen.
+        if (!mListeningForWebVrActivateBeforePause && !mRequestedWebVR && !isVrShellEnabled()) {
+            mVrDaydreamApi.launchVrHomescreen();
+            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);
             }
         }
 
         mRequestedWebVR = false;
@@ skipping 104 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);
 }