Show layer borders for scrollbar layers

Show layer borders for scrollbar layers
https://bugs.webkit.org/show_bug.cgi?id=76888

Source/WebCore:

Reviewed by Beth Dakin.

When compositing layer borders are showing, show the borders
for scrollbars layers. This reduces confusion about whether scrollbars
are rendering into their own layers.

Requires a new parameter to two GraphicsLayerClient methods.

* platform/graphics/GraphicsLayer.h:
(WebCore::GraphicsLayer::showDebugBorders):
(WebCore::GraphicsLayer::showRepaintCounter):
* platform/graphics/GraphicsLayerClient.h:
* rendering/RenderLayerBacking.cpp:
(WebCore::RenderLayerBacking::showDebugBorders):
(WebCore::RenderLayerBacking::showRepaintCounter):
* rendering/RenderLayerBacking.h:
* rendering/RenderLayerCompositor.cpp:
(WebCore::RenderLayerCompositor::showDebugBorders):
(WebCore::RenderLayerCompositor::showRepaintCounter):
* rendering/RenderLayerCompositor.h:

Source/WebKit/chromium:

Reviewed by Beth Dakin.

Update for new signature of GraphicsLayerClient::showDebugBorders()
and GraphicsLayerClient::showRepaintCounter().

* src/NonCompositedContentHost.cpp:
(WebKit::NonCompositedContentHost::showDebugBorders):
(WebKit::NonCompositedContentHost::showRepaintCounter):
* src/NonCompositedContentHost.h:
* src/PageOverlay.cpp:
(WebKit::OverlayGraphicsLayerClientImpl::showDebugBorders):
(WebKit::OverlayGraphicsLayerClientImpl::showRepaintCounter):
* tests/ImageLayerChromiumTest.cpp:
(WebCore::MockGraphicsLayerClient::showDebugBorders):
(WebCore::MockGraphicsLayerClient::showRepaintCounter):

Source/WebKit/win:

Reviewed by Beth Dakin.

Update for new signature of GraphicsLayerClient::showDebugBorders()
and GraphicsLayerClient::showRepaintCounter().

* WebView.cpp:
(WebView::showDebugBorders):
(WebView::showRepaintCounter):
* WebView.h:

Source/WebKit2:

Reviewed by Beth Dakin.

Update for new signatures of GraphicsLayerClient::showDebugBorders()
and GraphicsLayerClient::showRepaintCounter().

* UIProcess/LayerTreeHostProxy.h:
(WebKit::LayerTreeHostProxy::showDebugBorders):
(WebKit::LayerTreeHostProxy::showRepaintCounter):
* WebProcess/WebPage/ca/LayerTreeHostCA.cpp:
(WebKit::LayerTreeHostCA::showDebugBorders):
(WebKit::LayerTreeHostCA::showRepaintCounter):
* WebProcess/WebPage/ca/LayerTreeHostCA.h:
* WebProcess/WebPage/qt/LayerTreeHostQt.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@105757 268f45cc-cd09-0410-ab3c-d52691b4dbfc