Adds keyboard functionality for videos.

third_party/WebKit/Source/modules/media_controls/MediaControlsImpl.cpp

 /*
  * Copyright (C) 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * 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 15 matching lines @@
 
 #include "modules/media_controls/MediaControlsImpl.h"
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "core/dom/ClientRect.h"
 #include "core/dom/Fullscreen.h"
 #include "core/dom/ResizeObserver.h"
 #include "core/dom/ResizeObserverCallback.h"
 #include "core/dom/ResizeObserverEntry.h"
 #include "core/dom/TaskRunnerHelper.h"
+#include "core/events/KeyboardEvent.h"
 #include "core/events/MouseEvent.h"
 #include "core/frame/Settings.h"
 #include "core/frame/UseCounter.h"
 #include "core/html/HTMLMediaElement.h"
 #include "core/html/HTMLVideoElement.h"
 #include "core/html/media/HTMLMediaElementControlsList.h"
 #include "core/html/track/TextTrackContainer.h"
 #include "core/html/track/TextTrackList.h"
 #include "core/layout/LayoutObject.h"
 #include "core/layout/LayoutTheme.h"
@@ skipping 713 matching lines @@
       StartHideMediaControlsTimer();
     return;
   }
 
   // If the user is interacting with the controls via the keyboard, don't hide
   // the controls. This will fire when the user tabs between controls (focusin)
   // or when they seek either the timeline or volume sliders (input).
   if (event->type() == EventTypeNames::focusin ||
       event->type() == EventTypeNames::input)
     ResetHideMediaControlsTimer();
+
+  if (event->IsKeyboardEvent()) {

[mlamouri (slow - plz ping), 2017/05/09 17:32:10]

I realised the other day (not sure why I was thinking about this) that this
might conflict with websites keyboard event handling. Should we add a check like
`MediaElement().ShouldShowControls()`? And add a test checking that these
shortcuts do not apply if `controls` isn't set?

[lethalantidote, 2017/05/18 00:03:34]

Done.

+    const String& key = ToKeyboardEvent(event)->key();
+    if (key == "Enter" || ToKeyboardEvent(event)->keyCode() == ' ') {
+      play_button_->OnMediaKeyboardEvent(event);
+      return;
+    }
+    if (key == "ArrowLeft" || key == "ArrowRight" || key == "Home" ||
+        key == "End") {
+      timeline_->OnMediaKeyboardEvent(event);
+      return;
+    }
+    if (key == "ArrowDown" || key == "ArrowUp") {
+      volume_slider_->OnMediaKeyboardEvent(event);
+      return;
+    }
+  }
 }
 
 void MediaControlsImpl::HideMediaControlsTimerFired(TimerBase*) {
   unsigned behavior_flags =
       hide_timer_behavior_flags_ | kIgnoreFocus | kIgnoreVideoHover;
   hide_timer_behavior_flags_ = kIgnoreNone;
   keep_showing_until_timer_fires_ = false;
 
   if (MediaElement().paused())
     return;
@@ skipping 350 matching lines @@
   visitor->Trace(cast_button_);
   visitor->Trace(overlay_cast_button_);
   visitor->Trace(media_event_listener_);
   visitor->Trace(window_event_listener_);
   visitor->Trace(orientation_lock_delegate_);
   MediaControls::Trace(visitor);
   HTMLDivElement::Trace(visitor);
 }
 
 }  // namespace blink