Merge 108100 - 2012-02-17 Nate Chapin <firstname.lastname@example.org>
[Chromium mac] Cursors and background images disappear.
The issue occurs because a CachedImage sees that it has no clients
and decide it is safe to purge its m_data buffer. However,
StyleCachedImage is holding a CachedResourceHandle to the
CachedImage, and it can still add a client later. If it does so,
the CachedImage says everything is loaded but has no data.
Reviewed by Adam Barth.
No new tests, since the known repros have resisted reduction.
Tested manually with chrome.angrybirds.com
couple of other sites.
* rendering/style/StyleCachedImage.h: Ensure the underlying
CachedImage has a client for the lifetime of the
StyleCachedImage and doesn't purge its buffer. Call
addClient(this) in the constructor and removeClient(this) in
the destructor, then ignore all cache callbacks.