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

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/size_f.h"
 #include "ui/gfx/vector2d_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 10 matching lines @@
   // layer.
   // There is no requirement that the return values of this method are
   // stable in time (two subsequent calls may yield different results).
   // The return value is not required to be related to the values passed in to
   // the SetTotalScrollOffset method in any way however it is required to be no
   // more than the value passed to the most recent SetMaxScrollOffset call.
   virtual gfx::Vector2dF GetTotalScrollOffset() = 0;
 
   // 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
   // page scale factor and limits are.
   virtual void SetTotalPageScaleFactorAndLimits(
       float page_scale_factor,
       float min_page_scale_factor,
       float max_page_scale_factor) = 0;
 
   // This is called by the compositor to notify the delegate what is the layer's
   // 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() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(LayerScrollOffsetDelegate);
 };
 
 }  // namespace cc
 
 #endif  // CC_INPUT_LAYER_SCROLL_OFFSET_DELEGATE_H_