Paint tab-loading throbbers into a ui::Layer.

chrome/browser/ui/views/tabs/tab_controller.h

Index: chrome/browser/ui/views/tabs/tab_controller.h
diff --git a/chrome/browser/ui/views/tabs/tab_controller.h b/chrome/browser/ui/views/tabs/tab_controller.h
index 3e8807be7b45ea6864b425b352a0ef765a75122f..feced12f86ba50c5ba7b897f5292b3cbe228f055 100644
--- a/chrome/browser/ui/views/tabs/tab_controller.h
+++ b/chrome/browser/ui/views/tabs/tab_controller.h
@@ -93,6 +93,11 @@ class TabController {
   // set to the clip (if |clip| is empty means no clip).
   virtual bool ShouldPaintTab(const Tab* tab, gfx::Rect* clip) = 0;
 
+  // Returns true if tab loading throbbers can be painted to a composited layer.
+  // This can only be done when the TabController can guarantee that nothing
+  // in the same window will redraw on top of the the favicon area of any tab.
+  virtual bool CanPaintThrobberToLayer() const = 0;
+
   // Returns true if tabs painted in the rectangular light-bar style.
   virtual bool IsImmersiveStyle() const = 0;