GitLab

        Reviewed by David Hyatt.

        https://bugs.webkit.org/show_bug.cgi?id=25250
        Allow platforms to snap the scroll thumb back to the drag origin
        during a drag.  Implement functions for Safari/Win and Chromium/Win
        to do this snapping at distances approximating the native ones.

        * platform/Scrollbar.cpp:
        (WebCore::Scrollbar::Scrollbar):
        (WebCore::Scrollbar::setValue):
        (WebCore::Scrollbar::scroll):
        (WebCore::Scrollbar::moveThumb):
        (WebCore::Scrollbar::setCurrentPos):
        (WebCore::Scrollbar::mouseMoved):
        (WebCore::Scrollbar::mouseDown):
        * platform/Scrollbar.h:
        * platform/ScrollbarTheme.h:
        (WebCore::ScrollbarTheme::shouldSnapBackToDragOrigin):
        * platform/chromium/ScrollbarThemeChromium.h:
        * platform/chromium/ScrollbarThemeChromiumLinux.cpp:
        (WebCore::ScrollbarThemeChromium::shouldSnapBackToDragOrigin):
        * platform/chromium/ScrollbarThemeChromiumWin.cpp:
        (WebCore::ScrollbarThemeChromium::shouldSnapBackToDragOrigin):
        * platform/win/ScrollbarThemeWin.cpp:
        (WebCore::ScrollbarThemeWin::shouldCenterOnThumb):
        (WebCore::ScrollbarThemeWin::shouldSnapBackToDragOrigin):
        * platform/win/ScrollbarThemeWin.h:



git-svn-id: svn://svn.chromium.org/blink/trunk@42721 bbb929c8-8fbe-4397-9dbb-9b2b20218538