Gamepad API: add support for gamepadconnected and gamepaddisconnected events

Source/core/frame/DOMWindow.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 87 matching lines @@
 #include "platform/graphics/media/MediaPlayer.h"
 #include "platform/weborigin/KURL.h"
 #include "platform/weborigin/SecurityOrigin.h"
 #include "platform/weborigin/SecurityPolicy.h"
 #include "public/platform/Platform.h"
 #include "wtf/MainThread.h"
 #include "wtf/MathExtras.h"
 #include "wtf/text/WTFString.h"
 #include <algorithm>
 
+// FIXME: this is a layering vilation.

[Inactive, 2014/03/14 19:46:08]

Yes, we don't want that :)

[kbalazs, 2014/03/14 23:51:27]

Done.

+#include "modules/gamepad/NavigatorGamepad.h"
+
 using std::min;
 using std::max;
 
 namespace WebCore {
 
 class PostMessageTimer FINAL : public SuspendableTimer {
 public:
     PostMessageTimer(DOMWindow& window, PassRefPtr<SerializedScriptValue> message, const String& sourceOrigin, PassRefPtr<DOMWindow> source, PassOwnPtr<MessagePortChannelArray> channels, SecurityOrigin* targetOrigin, PassRefPtr<ScriptCallStack> stackTrace)
         : SuspendableTimer(window.document())
         , m_window(window)
@@ skipping 1393 matching lines @@
         UseCounter::count(document(), UseCounter::DocumentBeforeUnloadRegistered);
         if (allowsBeforeUnloadListeners(this)) {
             // This is confusingly named. It doesn't actually add the listener. It just increments a count
             // so that we know we have listeners registered for the purposes of determining if we can
             // fast terminate the renderer process.
             addBeforeUnloadEventListener(this);
         } else {
             // Subframes return false from allowsBeforeUnloadListeners.
             UseCounter::count(document(), UseCounter::SubFrameBeforeUnloadRegistered);
         }
+    } else if (eventType == EventTypeNames::gamepadconnected || eventType == EventTypeNames::gamepaddisconnected) {

[sof, 2014/03/14 20:52:43]

Just above these special cases, DOMWindow observers are notified about the event
listener being added. I think you can hook in your sampling trigger that way.
Grep for implementations of DOMWindowLifecycleObserver to see how.

[kbalazs, 2014/03/14 23:51:27]

Wonderful, thanks. Together with
FrameLoaderClientImpl::dispatchDidClearWindowObjectInWorld this lead me to a
solution.

+        // If an event listener is added for gamepad events sample the gamepads once to start monitoring gamepad state.
+        // FIXME: we need to instantiate NavigatorGamepad here so that it can listen to the events.
+        // Otherwise it would only be created when js calls getGamepads() or webkitGetGamepads() and we cannot assume that
+        // it will happen before a gamepad is connected. But this is a layering violation because NavigatorGamepad lives
+        // in modules.
+        NavigatorGamepad::getGamepads(navigator());

[Inactive, 2014/03/14 19:46:08]

You should probably take a look at
FrameLoaderClientImpl::dispatchDidClearWindowObjectInWorld(DOMWrapperWorld*
world) but abarth@ may have a better idea.

[kbalazs, 2014/03/14 23:51:27]

Done.

     }
 
     return true;
 }
 
 bool DOMWindow::removeEventListener(const AtomicString& eventType, EventListener* listener, bool useCapture)
 {
     if (!EventTarget::removeEventListener(eventType, listener, useCapture))
         return false;
 
@@ skipping 283 matching lines @@
     return static_cast<DOMWindowLifecycleNotifier&>(LifecycleContext<DOMWindow>::lifecycleNotifier());
 }
 
 PassOwnPtr<LifecycleNotifier<DOMWindow> > DOMWindow::createLifecycleNotifier()
 {
     return DOMWindowLifecycleNotifier::create(this);
 }
 
 
 } // namespace WebCore