[iOS] Show external device name/type in placeholder

[iOS] Show external device name/type in placeholder
https://bugs.webkit.org/show_bug.cgi?id=129723

Reviewed by Jer Noble.

Source/WebCore:

Make the name and type of the external device available to the JS based controls.
* Modules/mediacontrols/MediaControlsHost.cpp:
(WebCore::MediaControlsHost::externalDeviceDisplayName):
(WebCore::MediaControlsHost::externalDeviceType):
* Modules/mediacontrols/MediaControlsHost.h:
* Modules/mediacontrols/MediaControlsHost.idl:

* Modules/mediacontrols/mediaControlsiOS.js:
(ControllerIOS.prototype.updateWirelessPlaybackStatus): Display device type-specific infomation
    in the placeholder image.

* WebCore.exp.in: Export new WebKitSystemInterface functions.

* platform/graphics/MediaPlayer.cpp:
(WebCore::MediaPlayer::wirelessPlaybackTargetName): Added.
(WebCore::MediaPlayer::wirelessPlaybackTargetType): Ditto.
* platform/graphics/MediaPlayer.h:
* platform/graphics/MediaPlayerPrivate.h:

* platform/graphics/avfoundation/objc/MediaPlayerPrivateAVFoundationObjC.h:
* platform/graphics/avfoundation/objc/MediaPlayerPrivateAVFoundationObjC.mm:
(WebCore::MediaPlayerPrivateAVFoundationObjC::wirelessPlaybackTargetType): Added.
(WebCore::MediaPlayerPrivateAVFoundationObjC::wirelessPlaybackTargetName): Ditto.

* platform/ios/WebCoreSystemInterfaceIOS.mm:
* platform/mac/WebCoreSystemInterface.h:
* platform/mac/WebCoreSystemInterface.mm:

Source/WebKit/mac:

* WebCoreSupport/WebSystemInterface.mm:
(InitWebCoreSystemInterface):

WebKitLibraries:

* WebKitSystemInterface.h:
* libWebKitSystemInterfaceLion.a:
* libWebKitSystemInterfaceMavericks.a:
* libWebKitSystemInterfaceMountainLion.a:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@165125 268f45cc-cd09-0410-ab3c-d52691b4dbfc