Allow play/pause on default controls to clear media errors.

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

Index: third_party/WebKit/Source/core/html/shadow/MediaControlElements.cpp
diff --git a/third_party/WebKit/Source/core/html/shadow/MediaControlElements.cpp b/third_party/WebKit/Source/core/html/shadow/MediaControlElements.cpp
index 36ef45117fe63fa5a41b48feb7d9b07465783d47..82afeba52278b707f4ea78d46bfc3d696dd6684d 100644
--- a/third_party/WebKit/Source/core/html/shadow/MediaControlElements.cpp
+++ b/third_party/WebKit/Source/core/html/shadow/MediaControlElements.cpp
@@ -284,6 +284,9 @@ PassRefPtrWillBeRawPtr<MediaControlPlayButtonElement> MediaControlPlayButtonElem
 void MediaControlPlayButtonElement::defaultEventHandler(Event* event)
 {
     if (event->type() == EventTypeNames::click) {
+        if (mediaElement().error())
+            mediaElement().load();

[philipj_slow, 2016/03/24 07:00:05]

I think an error doesn't actually set paused to true, at least I can't see where
that happens. So it might happen that this still looks like a pause button, but
pressing it reloads and plays. Better than nothing of course, but is that what
you were hoping for?

Something to consider could be a "play again" icon, which is used at the end of
playback and also after an error. That way it'd be a bit more obvious what the
button does before clicking it. We have that as an overlay button in Opera for
Android, something I'd like to upstream. I don't think that needs to block this
CL of course, but do you think it would make sense?

[DaleCurtis, 2016/03/24 18:50:16]

Ah, I thought that was a bug, I was going to hunt it down today. You're correct
that it is stuck in the paused state when it dies. Errors do cause a reset of
the controls though, so we could have them toggle the paused / error state when
MediaControls::reset() is called.

I agree that we should have some iconography here. Either Opera's button or
reach out to the visual design team for a new material design button. Play again
sounds like a good choice. Though, I actually like the idea of a tiny sad
tab-like play button. Might be useful in differentiating reports from users. 

I don't think we need to make any update in this CL though -- especially since
desktop and mobile controls are different at present. I'd prefer to make any
updates after we've removed the old controls or limit them to the new UI.

+
         mediaElement().togglePlayState();
         updateDisplayType();
         event->setDefaultHandled();