Adds keyboard functionality for videos.

third_party/WebKit/Source/core/html/HTMLElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004-2008, 2013, 2014 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2011 Motorola Mobility. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 911 matching lines @@
     if (RuntimeEnabledFeatures::hideNonceContentAttributeEnabled() &&
         InActiveDocument() &&
         GetDocument().GetContentSecurityPolicy()->HasHeaderDeliveredPolicy()) {
       setAttribute(nonceAttr, g_empty_atom);
     }
   }
 
   return kInsertionDone;
 }
 
+bool HTMLElement::IsSpatialNavigationActive() {
+    return IsSpatialNavigationEnabled(GetDocument().GetFrame());

[mlamouri (slow - plz ping), 2017/05/24 08:49:15]

Maybe just make this call in MediaControlsImpl instead of adding it to
HTMLElement?

[lethalantidote, 2017/05/24 18:46:08]

Tried doing that. It's not directly accessible due to BUILD visibility. Wasnt
sure if I should be messing with that (also tried and didn't figure out how to
get to visible. Willing to give it another go if this is preferable.) 

[mlamouri (slow - plz ping), 2017/05/30 10:22:41]

I think you would simply need to add CORE_EXPORT to `bool
IsSpatialNavigationEnabled(const LocalFrame*);` in SpatialNavigation.h and
include "core/CoreExport.h".

This should work:
`CORE_EXPORT bool IsSpatialNavigationEnabled(const LocalFrame*);`

You can find an example here:
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/dom/Range...

[lethalantidote, 2017/05/30 19:48:12]

Done. The example was very helpful to me.

+}
+
 void HTMLElement::AddHTMLLengthToStyle(MutableStylePropertySet* style,
                                        CSSPropertyID property_id,
                                        const String& value,
                                        AllowPercentage allow_percentage) {
   HTMLDimension dimension;
   if (!ParseDimensionValue(value, dimension))
     return;
   if (property_id == CSSPropertyWidth &&
       (dimension.IsPercentage() || dimension.IsRelative())) {
     UseCounter::Count(GetDocument(), UseCounter::kHTMLElementDeprecatedWidth);
@@ skipping 278 matching lines @@
 
 #ifndef NDEBUG
 
 // For use in the debugger
 void dumpInnerHTML(blink::HTMLElement*);
 
 void dumpInnerHTML(blink::HTMLElement* element) {
   printf("%s\n", element->innerHTML().Ascii().data());
 }
 #endif