Unify Android Webview and Chrome's fling

cc/trees/layer_tree_host_impl.cc

 // Copyright 2011 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.
 
 #include "cc/trees/layer_tree_host_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <set>
@@ skipping 372 matching lines @@
   if (EvictedUIResourcesExist()) {
     TRACE_EVENT_INSTANT0(
         "cc", "LayerTreeHostImpl::CanDraw UI resources evicted not recreated",
         TRACE_EVENT_SCOPE_THREAD);
     return false;
   }
   return true;
 }
 
 void LayerTreeHostImpl::Animate(base::TimeTicks monotonic_time) {
-  if (input_handler_client_)
-    input_handler_client_->Animate(monotonic_time);
+  if (!root_layer_scroll_offset_delegate_ ||
+      (CurrentlyScrollingLayer() != InnerViewportScrollLayer() &&
+       CurrentlyScrollingLayer() != OuterViewportScrollLayer())) {
+    AnimateInput(monotonic_time);
+  }
   AnimatePageScale(monotonic_time);
   AnimateLayers(monotonic_time);
   AnimateScrollbars(monotonic_time);
   AnimateTopControls(monotonic_time);
 }
 
 void LayerTreeHostImpl::PrepareTiles() {
   if (!tile_manager_)
     return;
   if (!tile_priorities_dirty_)
@@ skipping 38 matching lines @@
     page_scale_animation_->ZoomTo(scaled_target_offset,
                                   page_scale,
                                   duration.InSecondsF());
   }
 
   SetNeedsAnimate();
   client_->SetNeedsCommitOnImplThread();
   client_->RenewTreePriority();
 }
 
+void LayerTreeHostImpl::SetNeedsAnimateInput() {
+  if (root_layer_scroll_offset_delegate_ &&
+      (CurrentlyScrollingLayer() == InnerViewportScrollLayer() ||
+       CurrentlyScrollingLayer() == OuterViewportScrollLayer())) {
+    if (root_layer_animation_callback_.is_null()) {
+      root_layer_animation_callback_ =
+          base::Bind(&LayerTreeHostImpl::AnimateInput, AsWeakPtr());
+    }
+    root_layer_scroll_offset_delegate_->SetNeedsAnimate(
+        root_layer_animation_callback_);
+    return;
+  }
+
+  SetNeedsAnimate();
+}
+
 bool LayerTreeHostImpl::IsCurrentlyScrollingLayerAt(
     const gfx::Point& viewport_point,
     InputHandler::ScrollInputType type) {
   if (!CurrentlyScrollingLayer())
     return false;
 
   gfx::PointF device_viewport_point =
       gfx::ScalePoint(viewport_point, device_scale_factor_);
 
   LayerImpl* layer_impl =
@@ skipping 2242 matching lines @@
 
 void LayerTreeHostImpl::ScrollEnd() {
   top_controls_manager_->ScrollEnd();
   ClearCurrentlyScrollingLayer();
 }
 
 InputHandler::ScrollStatus LayerTreeHostImpl::FlingScrollBegin() {
   if (!active_tree_->CurrentlyScrollingLayer())
     return SCROLL_IGNORED;
 
-  if (settings_.ignore_root_layer_flings &&
-      (active_tree_->CurrentlyScrollingLayer() == InnerViewportScrollLayer() ||
-       active_tree_->CurrentlyScrollingLayer() == OuterViewportScrollLayer())) {
-    ClearCurrentlyScrollingLayer();
-    return SCROLL_IGNORED;
-  }
-
   if (!wheel_scrolling_) {
     // Allow the fling to lock to the first layer that moves after the initial
     // fling |ScrollBy()| event.
     did_lock_scrolling_layer_ = false;
     should_bubble_scrolls_ = false;
   }
 
   return SCROLL_STARTED;
 }
 
@@ skipping 212 matching lines @@
   LayerImpl* scroll_layer = OuterViewportScrollLayer()
                                 ? OuterViewportScrollLayer()
                                 : InnerViewportScrollLayer();
 
   gfx::Vector2dF unused_delta = scroll_layer->ScrollBy(scroll_delta);
 
   if (!unused_delta.IsZero() && (scroll_layer == OuterViewportScrollLayer()))
     InnerViewportScrollLayer()->ScrollBy(unused_delta);
 }
 
+void LayerTreeHostImpl::AnimateInput(base::TimeTicks monotonic_time) {
+  DCHECK(proxy_->IsImplThread());
+  // TODO(jdduke): Skip when scrolling the root layer with an offset delegate?
+  if (input_handler_client_)
+    input_handler_client_->Animate(monotonic_time);
+}
+
 void LayerTreeHostImpl::AnimatePageScale(base::TimeTicks monotonic_time) {
   if (!page_scale_animation_)
     return;
 
   gfx::ScrollOffset scroll_total = active_tree_->TotalScrollOffset();
 
   if (!page_scale_animation_->IsAnimationStarted())
     page_scale_animation_->StartAnimation(monotonic_time);
 
   active_tree_->SetPageScaleOnActiveTree(
@@ skipping 410 matching lines @@
   new_target.SetToMin(layer_impl->MaxScrollOffset());
 
   curve->UpdateTarget(
       animation->TrimTimeToCurrentIteration(CurrentBeginFrameArgs().frame_time)
           .InSecondsF(),
       new_target);
 
   return true;
 }
 }  // namespace cc