Adds keyboard functionality for videos.

third_party/WebKit/Source/core/html/shadow/MediaControls.cpp

Index: third_party/WebKit/Source/core/html/shadow/MediaControls.cpp
diff --git a/third_party/WebKit/Source/core/html/shadow/MediaControls.cpp b/third_party/WebKit/Source/core/html/shadow/MediaControls.cpp
index 6fcf2642e672bbb9fa145f243b43bcf7045fa993..e77ba7dad0f7015c91a02b78fa78dc83f52c7952 100644
--- a/third_party/WebKit/Source/core/html/shadow/MediaControls.cpp
+++ b/third_party/WebKit/Source/core/html/shadow/MediaControls.cpp
@@ -33,6 +33,7 @@
 #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"
@@ -751,6 +752,26 @@ void MediaControls::defaultEventHandler(Event* event) {
       startHideMediaControlsTimer();
     return;
   }
+
+  if (event->type() == EventTypeNames::input) {

[mlamouri (slow - plz ping), 2017/03/27 13:02:12]

stupid question: why is that?

[CJ, 2017/04/08 00:31:27]

So we don't hide media controls while manipulating the volume/timeline. It
partially just does what steimel@ is doing in the mediacontrols bug he is
working on. 

+    resetHideMediaControlsTimer();
+  }
+
+  if (event->isKeyboardEvent()) {
+    const String& key = toKeyboardEvent(event)->key();
+    if (key == "Enter" || key == " ") {
+      m_playButton->onMediaKeyboardEvent(event);
+      return;
+    }
+    if (key == "ArrowLeft" || key == "ArrowRight") {
+      timelineElement()->onMediaKeyboardEvent(event);
+      return;
+    }
+    if (key == "ArrowDown" || key == "ArrowUp") {
+      volumeSliderElement()->onMediaKeyboardEvent(event);
+      return;
+    }
+  }
 }
 
 void MediaControls::hideMediaControlsTimerFired(TimerBase*) {