Unify Android Webview and Chrome's fling

cc/input/layer_scroll_offset_delegate.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_INPUT_LAYER_SCROLL_OFFSET_DELEGATE_H_
 #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/geometry/scroll_offset.h"
 #include "ui/gfx/geometry/size_f.h"
 
 namespace cc {
 
 // The LayerScrollOffsetDelegate allows for the embedder to take ownership of
 // the scroll offset of the root layer.
 //
 // The LayerScrollOffsetDelegate is only used on the impl thread.
 class LayerScrollOffsetDelegate {
@@ skipping 18 matching lines @@
   virtual void UpdateRootLayerState(
       const gfx::ScrollOffset& total_scroll_offset,
       const gfx::ScrollOffset& max_scroll_offset,
       const gfx::SizeF& scrollable_size,
       float page_scale_factor,
       float min_page_scale_factor,
       float max_page_scale_factor) = 0;
 
   // This is called by the compositor to check whether a delegate-managed fling
   // is active or not.
+  // TODO(jdduke): Remove?

[jdduke (slow), 2015/05/04 22:11:48]

Should we rename this to |IsExternalScrollActive()| (and so on up the chain)?

[hush (inactive), 2015/05/05 21:15:32]

Yes. Will do. I will also remove it when smooth scrolling logic is in chrome.

   virtual bool IsExternalFlingActive() const = 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() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(LayerScrollOffsetDelegate);
 };
 
 }  // namespace cc
 
 #endif  // CC_INPUT_LAYER_SCROLL_OFFSET_DELEGATE_H_