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

android_webview/browser/browser_view_renderer.h

Index: android_webview/browser/browser_view_renderer.h
diff --git a/android_webview/browser/browser_view_renderer.h b/android_webview/browser/browser_view_renderer.h
index ee6aa29914b2c8fdca6fada0ab33a5f3bf0516b6..bb5c9c7cf81462ffd143814ddb0fc8c56ff1ec0a 100644
--- a/android_webview/browser/browser_view_renderer.h
+++ b/android_webview/browser/browser_view_renderer.h
@@ -72,6 +72,7 @@ class BrowserViewRenderer : public content::SynchronousCompositorClient {
   void OnSizeChanged(int width, int height);
   void OnAttachedToWindow(int width, int height);
   void OnDetachedFromWindow();
+  void OnComputeScroll(base::TimeTicks animation_time);
 
   // Sets the scale for logical<->physical pixel conversions.
   void SetDipScale(float dip_scale);
@@ -104,6 +105,7 @@ class BrowserViewRenderer : public content::SynchronousCompositorClient {
                             float min_page_scale_factor,
                             float max_page_scale_factor) override;
   bool IsExternalFlingActive() const override;
+  void SetNeedsAnimateFling(const AnimationCallback& fling_animation) override;
   void DidOverscroll(gfx::Vector2dF accumulated_overscroll,
                      gfx::Vector2dF latest_overscroll_delta,
                      gfx::Vector2dF current_fling_velocity) override;
@@ -145,6 +147,10 @@ class BrowserViewRenderer : public content::SynchronousCompositorClient {
   // compositor that are not directly exposed here.
   void ForceFakeCompositeSW();
 
+  // Honor the requested fling animation as contained in
+  // |pending_fling_animation_|.
+  void FlushPendingFlingAnimation(base::TimeTicks animation_time);
+
   gfx::Vector2d max_scroll_offset() const;
 
   size_t CalculateDesiredMemoryPolicy();
@@ -194,6 +200,11 @@ class BrowserViewRenderer : public content::SynchronousCompositorClient {
 
   gfx::Size size_;
 
+  // Used to drive a fling animation as requested by the compositor. This acts
+  // as a  single-shot animation; the compositor will continually post an
+  // animation callback as long as they're required.
+  AnimationCallback pending_fling_animation_;
+
   // Current scroll offset in CSS pixels.
   gfx::Vector2dF scroll_offset_dip_;