Add port-specific control over rendering of media control elements

[Andrew Scherkus]

Ports should be able to control whether a media control element is rendered or not.

[Andrew Scherkus]

Created attachment 39891 [details]
Draft

This is a draft of deferring the decision on rendering a media control element to the RenderTheme.

This is my first real dive into Element/RenderObject/Style/Theme interaction, so feel free to point out my mistakes :)

[Andrew Scherkus]

The overall change is:
 1) Media control elements will always create a renderer
 2) RenderTheme decides whether those renderers will be visible based on inspecting the HTMLMediaElement

[Andrew Scherkus]

Forgot I had left my previous bug open.  Closing.

*** This bug has been marked as a duplicate of bug 28689 ***

[Eric Carlson]

> +
> +    // Alternatively we could pass in the theme for fine-tuned adjustment.  If
> +    // we keep it as simply setting display to NONE then I might rename this method
> +    // shouldDisplayMediaControlPart instead.
> +    if (!renderer->theme()->shouldRenderMediaControlPart(renderer))
> +        style->setDisplay(NONE);

This shouldn't be necessary. I think if have both MediaControlElement:: rendererIsNeeded and MediaControlInputElement:: rendererIsNeeded call the theme method it should just work.

>  bool MediaControlMuteButtonElement::rendererIsNeeded(RenderStyle* style)
>  {
> -    return MediaControlInputElement::rendererIsNeeded(style) && !disabled();
> +    // All subclasses will probably end up NOT implementing this method anymore.
> +    return MediaControlInputElement::rendererIsNeeded(style);

We do want to call the the base class method, an element could not need a renderer for other reasons (eg. CSS).

[Eric Carlson]

oops, wrong bug.