Another report: https://twitter.com/jgpicatoste/status/878254858700075009

Tested the issue on windows 10 & 7 using chrome M59 #59.0.3071.115 and canary M61 #61.0.3142.3 and followed below steps:

1. launched chrome and connected logitech f310 gamepad and navigated to https://www.scirra.com/labs/gamepaddemo/ .
2. Once the gamepad is detected ,opened new tab and opened https://editor.construct.net.
3. In the search field (under the Construct 3 logo), typed "gamepad"
4. Double-clicked the "gamepad control" demo that is listed
5. Clicked the "Play" button in the toolbar at the top, and approved any popup window prompts
6. Observed that no gamepad detected.

Attached screencast for reference.

@ash-- Could you please confirm if this is the issue you are talking about or if we have missed any steps in reproducing the issue and help us by providing the expected result screenshot or video, for better understanding.


Thanks!

Deleted: 736289.mp4 5.1 MB

	736289.mp4 5.1 MB View Download

That is indeed the issue, the video is just about right but the issue only reproduces when using the normal Run button (in the video the Debug button is clicked instead).

We just published an update that accidentally works around this by changing the URL of the preview to a different origin. This issue still reproduces if you use this URL instead:

https://editor.construct.net/r41/

So it seems the issue is if you open a popup window on the same origin as the page, the top-level frame in the popup cannot access any gamepads. You can verify in the popup in the console that navigator.getGamepads() only returns an array of null entries, even after trying to use the gamepad.

Thank you for providing more feedback. Adding requester "hdodda@chromium.org" to the cc list and removing "Needs-Feedback" label.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

I also tried to reproduce the issue in a minimal test, but it worked. There must be something different about Construct 3 that breaks it.

@ash--- We are not able to get what you are exactly trying to communicate .. Could you please prvide us the screencast of the steps to reproduce the issue , that would help in better understanding.

Screencast tool :
https://screencast-o-matic.en.softonic.com/

Thanks!

This is failing because NavigatorGamepad can't get an execution context. In NavigatorGamepad::StartUpdatingIfAttached we grab the context and cast it to a Document. In the failing case, this context is NULL; in the accidental workaround, it finds the context and casts successfully.

 Issue 711252  has been merged into this issue.

Thanks to japhet@ for figuring this out. NavigatorGamepad gets the LocalFrame via the ExecutionContext, which it accesses through the ContextLifecycleObserver interface. In some cases, the ExecutionContext can be NULL even when the DOMWindow is still active.

From ContextLifecycleObserver.h:

// There is a subtle difference between the timing when the context gets
// detached and the timing when the window gets detached. In common cases,
// these two happen at the same timing. The only exception is a case where
// a frame navigates from an initial empty document to another same-origin
// document. In this case, a Document is recreated but a DOMWindow is reused.
// Hence, in the navigated document ContextClient::getExecutionContext()
// returns null while DOMWindowClient::domWindow() keeps returning the window.

We're hitting this case because the popup is initially created with an empty document and then navigates to a same-origin document. To fix, NavigatorGamepad should access the LocalFrame through the DOMWindowClient interface, which will continue to return the correct LocalFrame and DOMWindow even after the empty document is destroyed.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4fca553939af1d2d33a49c4ca2df1727a020be09

commit 4fca553939af1d2d33a49c4ca2df1727a020be09
Author: Matt Reynolds <mattreynolds@google.com>
Date: Tue Oct 10 21:45:51 2017

Fix "Gamepad API does not work in a popup window"

NavigatorGamepad previously accessed the LocalFrame and LocalDOMWindow
through the ExecutionContext provided through the
ContextLifecycleObserver interface. In some cases the ExecutionContext
returned by the interface method is NULL while the DOMWindow is still
active. This can occur when a window navigates from an empty document
to a same-origin document. The ExecutionContext is recreated but the
window is reused.

This CL fixes this issue by instead having NavigatorGamepad access the
LocalFrame and LocalDOMWindow through the DOMWindowClient interface,
which will return the correct frame and window when the
ExecutionContext is destroyed.

BUG= 736289 

Change-Id: I5f26f05b7599c1b708f1ddc358949fb872a9a8ec
Reviewed-on: https://chromium-review.googlesource.com/667864
Commit-Queue: Matt Reynolds <mattreynolds@chromium.org>
Reviewed-by: Brandon Jones <bajones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#507782}
[modify] https://crrev.com/4fca553939af1d2d33a49c4ca2df1727a020be09/third_party/WebKit/Source/modules/gamepad/NavigatorGamepad.cpp
[modify] https://crrev.com/4fca553939af1d2d33a49c4ca2df1727a020be09/third_party/WebKit/Source/modules/gamepad/NavigatorGamepad.h