Reviewed by David Levin.

        Reimplement default media UI for Mac Chromium to match the style
        of the Windows and Linux versions.  Also breaks the dependency
        on the internal wk* functions that were previously used to
        render the media controller widgets.
        https://bugs.webkit.org/show_bug.cgi?id=29161

        No media layout tests are currently enabled in Mac Chromium, so
        nothing needs rebaselineing, etc.

        This is a recommit of r48438 with a compile fix and merges of
        recent changes to the file.

        * css/mediaControlsChromium.css:
        * rendering/RenderThemeChromiumMac.h:
        * rendering/RenderThemeChromiumMac.mm:
        (WebCore::mediaElementParent):
        (WebCore::RenderThemeChromiumMac::extraMediaControlsStyleSheet):
        (WebCore::mediaSliderThumbImage):
        (WebCore::mediaVolumeSliderThumbImage):
        (WebCore::RenderThemeChromiumMac::paintSliderTrack):
        (WebCore::RenderThemeChromiumMac::adjustSliderThumbSize):
        (WebCore::RenderThemeChromiumMac::paintMediaButtonInternal):
        (WebCore::RenderThemeChromiumMac::paintMediaPlayButton):
        (WebCore::RenderThemeChromiumMac::paintMediaMuteButton):
        (WebCore::RenderThemeChromiumMac::paintMediaSliderTrack):
        (WebCore::RenderThemeChromiumMac::paintMediaVolumeSliderTrack):
        (WebCore::RenderThemeChromiumMac::paintMediaSliderThumb):
        (WebCore::RenderThemeChromiumMac::paintMediaVolumeSliderThumb):
        (WebCore::RenderThemeChromiumMac::paintMediaControlsBackground):
        * rendering/RenderThemeChromiumSkia.cpp:
        (WebCore::RenderThemeChromiumSkia::adjustSliderThumbSize):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@48499 268f45cc-cd09-0410-ab3c-d52691b4dbfc