NOT FOR LANDING - [WebView] Allow fling animation via the LayerScrollOffsetDelegate

cc/input/layer_scroll_offset_delegate.h

Index: cc/input/layer_scroll_offset_delegate.h
diff --git a/cc/input/layer_scroll_offset_delegate.h b/cc/input/layer_scroll_offset_delegate.h
index 2da5f13befbd83739448f6e289a3f2b58e033ae7..d83d272fdaa7faf61e49faaa60e4349562618142 100644
--- a/cc/input/layer_scroll_offset_delegate.h
+++ b/cc/input/layer_scroll_offset_delegate.h
@@ -6,6 +6,8 @@
 #define CC_INPUT_LAYER_SCROLL_OFFSET_DELEGATE_H_
 
 #include "base/basictypes.h"
+#include "base/callback_forward.h"
+#include "base/time/time.h"
 #include "ui/gfx/size_f.h"
 #include "ui/gfx/vector2d_f.h"
 
@@ -36,6 +38,7 @@ class LayerScrollOffsetDelegate {
 
   // This is called by the compositor to check whether a delegate-managed fling
   // is active or not.
+  // TODO(jdduke): Remove?

[mkosiba (inactive), 2014/05/15 13:48:51]

maybe. This is still used by stuff like pageUp/pageDown and
requestChildRectangleOnScreen. If we take it out those animations might become
choppy. OTOH those APIs are probably not used that much so it could be fine.

[jdduke (slow), 2014/05/15 14:15:43]

Gotcha, I suppose we could leave in for now.

   virtual bool IsExternalFlingActive() const = 0;
 
   // This is called by the compositor to notify the delegate what is the current
@@ -49,6 +52,11 @@ class LayerScrollOffsetDelegate {
   // scrollable size is.
   virtual void SetScrollableSize(const gfx::SizeF& scrollable_size) = 0;
 
+  // This is called by the compositor when a fling hitting the root layer
+  // requires a scheduled animation update.
+  typedef base::Callback<void(base::TimeTicks)> AnimationCallback;
+  virtual void SetNeedsAnimate(const AnimationCallback& animation) = 0;
+
  protected:
   LayerScrollOffsetDelegate() {}
   virtual ~LayerScrollOffsetDelegate() {}