Actually I'm not sure if we can even do this at the moment.

We can check the page is focused with m_navigatorVR->page()->focusController().isFocused(), but is there a notion of the frame the script is running in that calls getPose() and others? We'd want to make sure only the script running in the focused frame can get pose data.

Focus is tracked per frame and that information should be available in the C++ world. Don't know how much is exposed to JS.

Ping Brandon; this is currently a P1 for M57.  Is there an action plan for how to address this?

If Brandon's plate is full, feel free to assign to me, though I'm not very familiar with blink how focus/frames/documents interact.

My plate is rather full right now. Be my guest.

Not yet sure if this is a bug, or intentional, but currently a page doesn't lose focus in multi-window mode if another activity is focused. Investigating and will file a bug if necessary, but that definitely blocks this from being implemented correctly.

Adding alexmos@, who has done work on frame focus across renderer and browser.

PMs, is this still seen as critical for M-57? I would rather just push this back to M-58.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/527310a8c856c31a016c8f9c9ddb90a5290aef5b

commit 527310a8c856c31a016c8f9c9ddb90a5290aef5b
Author: mthiesse <mthiesse@chromium.org>
Date: Mon Feb 06 18:31:06 2017

Provide WebVR pose data only to the focused frame.

Testing is tracked in  issue 679827 . For now this is manually tested.

BUG= 683322 ,  686890 

Review-Url: https://codereview.chromium.org/2668003003
Cr-Commit-Position: refs/heads/master@{#448315}

[modify] https://crrev.com/527310a8c856c31a016c8f9c9ddb90a5290aef5b/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellImpl.java
[modify] https://crrev.com/527310a8c856c31a016c8f9c9ddb90a5290aef5b/third_party/WebKit/Source/core/page/BUILD.gn
[add] https://crrev.com/527310a8c856c31a016c8f9c9ddb90a5290aef5b/third_party/WebKit/Source/core/page/FocusChangedObserver.cpp
[add] https://crrev.com/527310a8c856c31a016c8f9c9ddb90a5290aef5b/third_party/WebKit/Source/core/page/FocusChangedObserver.h
[modify] https://crrev.com/527310a8c856c31a016c8f9c9ddb90a5290aef5b/third_party/WebKit/Source/core/page/FocusController.cpp
[modify] https://crrev.com/527310a8c856c31a016c8f9c9ddb90a5290aef5b/third_party/WebKit/Source/core/page/FocusController.h
[modify] https://crrev.com/527310a8c856c31a016c8f9c9ddb90a5290aef5b/third_party/WebKit/Source/modules/vr/NavigatorVR.cpp
[modify] https://crrev.com/527310a8c856c31a016c8f9c9ddb90a5290aef5b/third_party/WebKit/Source/modules/vr/NavigatorVR.h
[modify] https://crrev.com/527310a8c856c31a016c8f9c9ddb90a5290aef5b/third_party/WebKit/Source/modules/vr/VRController.cpp
[modify] https://crrev.com/527310a8c856c31a016c8f9c9ddb90a5290aef5b/third_party/WebKit/Source/modules/vr/VRController.h
[modify] https://crrev.com/527310a8c856c31a016c8f9c9ddb90a5290aef5b/third_party/WebKit/Source/modules/vr/VRDisplay.cpp
[modify] https://crrev.com/527310a8c856c31a016c8f9c9ddb90a5290aef5b/third_party/WebKit/Source/modules/vr/VRDisplay.h

Is there still more work to do here?

 issue 686232  needs to be fixed before it functions correctly, but nothing more to do for this bug.

Not sure if we want to mark it fixed before it actually works properly though.

Marking this as fixed.

Remaining issues are due to the android-specific bug where webpage focus doesn't accurately track input focus. In multi-window mode both windows are considered to have input focus by blink, so one of them effectively at random will get poses.

Also when the app is backgrounded blink doesn't realize it loses input focus, but this is less of an issue because we don't send poses when the app is paused.