https://bugs.webkit.org/show_bug.cgi?id=106972

Reviewed by Eric Carlson.

Source/WebCore:

Allow the MediaPlayerPrivateQTKit engine to be disabled by adding a
runtime setting to Settings. Make the setting 'live' by requerying the
installed media engines when the setting changes.

* WebCore.exp.in: Add new symbols to export list.
* page/Settings.cpp: Add new gQTKitEnabled global.
(WebCore::Settings::setAVFoundationEnabled): Requery media engines.
(WebCore::Settings::setQTKitEnabled): Ditto. Setter for global setting variable.
* page/Settings.h:
(WebCore::Settings::isQTKitEnabled): Getter for same.
* platform/graphics/MediaPlayer.cpp:
(WebCore::installedMediaEngines): Check isQTKitEnabled() before adding
    MediaPlayerPrivateQTKit engine.
* html/HTMLMediaElement.cpp:
(WebCore::HTMLMediaElement::requeryMediaEngines): Pass through to MediaPlayer.
* html/HTMLMediaElement.h:
* platform/graphics/MediaPlayer.cpp:
(WebCore::installedMediaEngines): Take an optional requery options parameter.
(WebCore::MediaPlayer::requeryMediaEngines): Pass through to installedMediaEngines().
* platform/graphics/MediaPlayer.h:

Source/WebKit/mac:

Add WebKit API to set QTKit enabled setting from user defaults.

* WebView/WebPreferenceKeysPrivate.h:
* WebView/WebPreferences.mm:
(+[WebPreferences initialize]): Set WebCore settings based on user defaults.
(-[WebPreferences setQTKitEnabled:]): Pass through to WebCore.
(-[WebPreferences isQTKitEnabled]): Ditto.
* WebView/WebPreferencesPrivate.h:
* WebView/WebView.mm:
(-[WebView _preferencesChanged:]): Synchronize WebKit/WebCore settings.

Source/WebKit2:

Add a WebKit2 API to access WebCore QTKitEnabled settings.

* Shared/WebPreferencesStore.h:
* UIProcess/API/C/WKPreferences.cpp:
(WKPreferencesSetQTKitEnabled): Pass through to WebCore.
(WKPreferencesGetQTKitEnabled): Ditto.
* UIProcess/API/C/WKPreferences.h:
* WebProcess/WebPage/WebPage.cpp:
(WebKit::WebPage::updatePreferences): Synchronize WebKit2/WebCore settings.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@139899 268f45cc-cd09-0410-ab3c-d52691b4dbfc