Reviewed by Kent Tamura.

        [Chromium] Add WebThemeEngineDRTMac so that Chromium DRT scrollbar rendering can match the Mac port's
        https://bugs.webkit.org/show_bug.cgi?id=51728

        Add implementation of the Mac WebThemeEngine that uses an NSScroller
        to render top-level scrollbars. This makes them match the Mac port's
        use of an NSScrollView, which means that we'll be able to share more
        pixel baselines.

        The new rendering code will not be activated until the
        USE_WEB_THEME_ENGINE_TO_PAINT_THUMB #define is fliped in
        ScrollbarThemeChromiumMac.

        * DumpRenderTree/DumpRenderTree.gypi:
        * DumpRenderTree/chromium/TestShellMac.mm:
        (platformInit):
        * DumpRenderTree/chromium/WebThemeEngineDRTMac.h: Added.
        * DumpRenderTree/chromium/WebThemeEngineDRTMac.mm: Added.
        (+[FakeActiveWindow alwaysActiveWindow]):
        (+[FakeActiveWindow alwaysInactiveWindow]):
        (-[FakeActiveWindow initWithActiveControls:]):
        (-[FakeActiveWindow _hasActiveControls]):
        (WebThemeEngineDRTMac::paintScrollbarThumb):
        (stateToHIEnableState):
        (WebThemeEngineDRTMac::paintHIThemeScrollbarThumb):
        (WebThemeEngineDRTMac::paintNSScrollerScrollbarThumb):
2010-12-30  Mihai Parparita  <mihaip@chromium.org>

        Reviewed by Kent Tamura.

        [Chromium] Add WebThemeEngineDRTMac so that Chromium DRT scrollbar rendering can match the Mac port's
        https://bugs.webkit.org/show_bug.cgi?id=51728

        Roll DEPS to pick up WebThemeEngine changes.

        * DEPS:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@74821 268f45cc-cd09-0410-ab3c-d52691b4dbfc