Move the AnimateInput paths for WebView around to not path through cc.

They don't need to go through cc, so let's not and this lets cc reason
about when/how things happen better.

Adds 2 new interfaces:
- SynchronousInputHandlerProxy. A limited view of the InputHandlerProxy
given out to WebView to control animating timing. It lets WebView call
SynchronouslyAnimate() to do animations. And if cc tried to also animate,
we'd hit a DCHECK.

- SynchronousInputHandler. An interface given to the InputHandlerProxy
as an alternate place to handle requests for animation. When it's
present animate requests go there instead of the usual InputHandler.

R=boliu, enne, hush, jdduke, sievers
BUG=522658
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1307203003

Cr-Commit-Position: refs/heads/master@{#348014}

2 files changed, 5 insertions, 6 deletions

diff --git a/cc/input/input_handler.h b/cc/input/input_handler.h
index 4852bdc..67a2c57 100644
--- a/cc/input/input_handler.h
+++ b/cc/input/input_handler.h
@@ -143,9 +143,13 @@ class CC_EXPORT InputHandler {
   // Request another callback to InputHandlerClient::Animate().
   virtual void SetNeedsAnimateInput() = 0;
 
+  // If there is a scroll active, this reports whether the scroll is on the
+  // root layer, or on some other sublayer.
+  virtual bool IsCurrentlyScrollingRoot() const = 0;
+
   // Whether the layer under |viewport_point| is the currently scrolling layer.
   virtual bool IsCurrentlyScrollingLayerAt(const gfx::Point& viewport_point,
-                                           ScrollInputType type) = 0;
+                                           ScrollInputType type) const = 0;
 
   virtual bool HaveWheelEventHandlersAt(const gfx::Point& viewport_point) = 0;
 
diff --git a/cc/input/layer_scroll_offset_delegate.h b/cc/input/layer_scroll_offset_delegate.h
index a0c0e0d..afd6e4b 100644
--- a/cc/input/layer_scroll_offset_delegate.h
+++ b/cc/input/layer_scroll_offset_delegate.h
@@ -44,11 +44,6 @@ class LayerScrollOffsetDelegate {
       float min_page_scale_factor,
       float max_page_scale_factor) = 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() {}