RenderWidget::WasRestored should repaint the view when accelerated compositing

is enabled. This fixes the case where restoring a previously-hidden accelerated
tab would not actually show its contents without mouse-moving within the tab's
contents.

Patch by Nat Duca (nduca@chromium.org)
R=darin
BUG=51306
TEST=Load the two URLS specified in original bug report into seperate tabs.
Switching tabs should show the content of the correct tab.

Originally reviewed at: http://codereview.chromium.org/3161023/show

Review URL: http://codereview.chromium.org/3176025

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@56814 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/renderer_host/render_widget_host.cc

@@ -225,8 +225,11 @@ void RenderWidgetHost::WasRestored() {
   BackingStore* backing_store = BackingStoreManager::Lookup(this);
   // If we already have a backing store for this widget, then we don't need to
   // repaint on restore _unless_ we know that our backing store is invalid.
+  // When accelerated compositing is on, we must always repaint, even when
+  // the backing store exists.
   bool needs_repainting;
-  if (needs_repainting_on_restore_ || !backing_store) {
+  if (needs_repainting_on_restore_ || !backing_store ||
+      is_gpu_rendering_active()) {
     needs_repainting = true;
     needs_repainting_on_restore_ = false;
   } else {