Early terminate flings when scrolling impossible

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 "base/basictypes.h"
@@ skipping 2316 matching lines @@
 
   // Scrolling along an axis resets accumulated root overscroll for that axis.
   if (did_scroll_x)
     accumulated_root_overscroll_.set_x(0);
   if (did_scroll_y)
     accumulated_root_overscroll_.set_y(0);
 
   accumulated_root_overscroll_ += unused_root_delta;
   bool did_overscroll = !unused_root_delta.IsZero();
   if (did_overscroll && input_handler_client_) {
-    DidOverscrollParams params;
-    params.accumulated_overscroll = accumulated_root_overscroll_;
-    params.latest_overscroll_delta = unused_root_delta;
-    params.current_fling_velocity = current_fling_velocity_;
-    input_handler_client_->DidOverscroll(params);
+    input_handler_client_->DidOverscroll(accumulated_root_overscroll_,
+                                         unused_root_delta);
   }
 
   return did_scroll_content || did_scroll_top_controls;
 }
 
 // This implements scrolling by page as described here:
 // http://msdn.microsoft.com/en-us/library/windows/desktop/ms645601(v=vs.85).aspx#_win32_The_Mouse_Wheel
 // for events with WHEEL_PAGESCROLL set.
 bool LayerTreeHostImpl::ScrollVerticallyByPage(const gfx::Point& viewport_point,
                                                ScrollDirection direction) {
@@ skipping 43 matching lines @@
 void LayerTreeHostImpl::OnRootLayerDelegatedScrollOffsetChanged() {
   DCHECK(root_layer_scroll_offset_delegate_ != NULL);
   client_->SetNeedsCommitOnImplThread();
 }
 
 void LayerTreeHostImpl::ClearCurrentlyScrollingLayer() {
   active_tree_->ClearCurrentlyScrollingLayer();
   did_lock_scrolling_layer_ = false;
   scroll_affects_scroll_handler_ = false;
   accumulated_root_overscroll_ = gfx::Vector2dF();
-  current_fling_velocity_ = gfx::Vector2dF();
 }
 
 void LayerTreeHostImpl::ScrollEnd() {
   if (top_controls_manager_)
     top_controls_manager_->ScrollEnd();
   ClearCurrentlyScrollingLayer();
   StartScrollbarAnimation();
 }
 
 InputHandler::ScrollStatus LayerTreeHostImpl::FlingScrollBegin() {
@@ skipping 10 matching lines @@
   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 ScrollStarted;
 }
 
-void LayerTreeHostImpl::NotifyCurrentFlingVelocity(
-    const gfx::Vector2dF& velocity) {
-  current_fling_velocity_ = velocity;
-}
-
 float LayerTreeHostImpl::DeviceSpaceDistanceToLayer(
     const gfx::PointF& device_viewport_point,
     LayerImpl* layer_impl) {
   if (!layer_impl)
     return std::numeric_limits<float>::max();
 
   gfx::Rect layer_impl_bounds(
       layer_impl->content_bounds());
 
   gfx::RectF device_viewport_layer_impl_bounds = MathUtil::MapClippedRect(
@@ skipping 589 matching lines @@
   swap_promise_monitor_.erase(monitor);
 }
 
 void LayerTreeHostImpl::NotifySwapPromiseMonitorsOfSetNeedsRedraw() {
   std::set<SwapPromiseMonitor*>::iterator it = swap_promise_monitor_.begin();
   for (; it != swap_promise_monitor_.end(); it++)
     (*it)->OnSetNeedsRedrawOnImpl();
 }
 
 }  // namespace cc