https://bugs.webkit.org/show_bug.cgi?id=93099

Patch by Arvid Nilsson <anilsson@rim.com> on 2012-08-03
Reviewed by Antonio Gomes.

The WebKit-thread overlays, like tap highlight, inspector highlight and
selection are all part of a separate graphics layer tree rooted in
WebPagePrivate::m_overlayLayer.

When LayerRenderer needs to schedule a commit to reactively render
tiles and resolve checkerboard, it does so through the root layer.
Since the overlay layer root didn't have a GraphicsLayerClient, there
was no implementation of GraphicsLayerClient::notifySyncRequired() to
call, and a commit was never scheduled, thus checkerboard never
resolved.

Fixed by adding a fallback implementation of GraphicsLayerClient in
WebPagePrivate and hooking up the overlay root to it. Also, this
implementation can be shared by the various overlays to avoide code
duplication, specifically to implement notifySyncRequired(),
showDebugBorders() and showRepaintCounter() only once.

Fixing this revealed a bug where the web page would get stuck in an
endless sequence of commits. It turned out that
WebPagePrivate::updateDelegatedOverlays() was called right in the
middle of the commit operation, after performing the webkit thread part
of the commit operation but before we continued on the compositing
thread. Since updateDelegatedOverlays() typically mutates layers, this
is very bad (layers should not be mutated mid-commit). The mutations
also cause a new commit to scheduled from within the current, which
results in an endless sequence of commits.

Fixed this latter bug by moving the updateDelegatedOverlays() call to
the beginning of the method where it can cause no harm. This is before
we mark the web page as no longer needing commit, so even if the
implementation flips the "needs commit" bit, we will immediately flip
it back and proceed with commit as usual.

PR 187458, 184377

* Api/WebPage.cpp:
(BlackBerry::WebKit::WebPagePrivate::overlayLayer):
(BlackBerry::WebKit::WebPagePrivate::commitRootLayerIfNeeded):
(WebKit):
(BlackBerry::WebKit::WebPagePrivate::notifySyncRequired):
(BlackBerry::WebKit::WebPagePrivate::showDebugBorders):
(BlackBerry::WebKit::WebPagePrivate::showRepaintCounter):
* Api/WebPage_p.h:
(WebPagePrivate):
(BlackBerry::WebKit::WebPagePrivate::notifyAnimationStarted):
(BlackBerry::WebKit::WebPagePrivate::paintContents):
* WebCoreSupport/InspectorOverlay.cpp:
(WebCore::InspectorOverlay::notifySyncRequired):
(WebCore::InspectorOverlay::showDebugBorders):
(WebCore::InspectorOverlay::showRepaintCounter):
* WebKitSupport/DefaultTapHighlight.cpp:
(BlackBerry::WebKit::DefaultTapHighlight::notifySyncRequired):
(BlackBerry::WebKit::DefaultTapHighlight::showDebugBorders):
(WebKit):
(BlackBerry::WebKit::DefaultTapHighlight::showRepaintCounter):
* WebKitSupport/DefaultTapHighlight.h:
(DefaultTapHighlight):
* WebKitSupport/SelectionOverlay.cpp:
(BlackBerry::WebKit::SelectionOverlay::notifySyncRequired):
(BlackBerry::WebKit::SelectionOverlay::showDebugBorders):
(WebKit):
(BlackBerry::WebKit::SelectionOverlay::showRepaintCounter):
* WebKitSupport/SelectionOverlay.h:
(SelectionOverlay):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@124615 268f45cc-cd09-0410-ab3c-d52691b4dbfc