Fix scrolling of full-frame pdf docs in accelerated compositing mode by forcing a full
frame invalidation on scroll offset changes. Current Pepper2D plugin
scrolling is fundamentally incompatible with how pages scroll in the accelerated compositing. Plugins rely on
shifting the existing backing and backfilling whereas the compositor scrolls by moving the viewport on top
of a fixed document.
BUG=chromium-os:18521
Review URL: http://codereview.chromium.org/
8100017
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@103831 0039d316-1c4b-4281-b951-d872f2087c98