cc: Damage layer on delegated scroll

cc/layers/layer_impl.cc

 // Copyright 2012 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/layers/layer_impl.h"
 
 #include "base/debug/trace_event.h"
 #include "base/debug/trace_event_argument.h"
 #include "base/json/json_reader.h"
 #include "base/strings/stringprintf.h"
@@ skipping 1061 matching lines @@
   scroll_offset_delegate_ = scroll_offset_delegate;
   if (scroll_offset_delegate_)
     scroll_offset_delegate_->SetTotalScrollOffset(total_offset);
 }
 
 bool LayerImpl::IsExternalFlingActive() const {
   return scroll_offset_delegate_ &&
          scroll_offset_delegate_->IsExternalFlingActive();
 }
 
+void LayerImpl::OnDelegatedScrollOffsetChanged() {
+  NoteLayerPropertyChangedForSubtree();
+  ScrollbarParametersDidChange(false);
+}
+
 void LayerImpl::SetScrollOffset(const gfx::ScrollOffset& scroll_offset) {
   SetScrollOffsetAndDelta(scroll_offset, ScrollDelta());
 }
 
 void LayerImpl::SetScrollOffsetAndDelta(const gfx::ScrollOffset& scroll_offset,
                                         const gfx::Vector2dF& scroll_delta) {
   bool changed = false;
 
   last_scroll_offset_ = scroll_offset;
 
@@ skipping 23 matching lines @@
 
     if (scroll_offset_delegate_) {
       scroll_offset_delegate_->SetTotalScrollOffset(
           ScrollOffsetWithDelta(scroll_offset_, scroll_delta));
     } else {
       scroll_delta_ = scroll_delta;
     }
   }
 
   if (changed) {
-    NoteLayerPropertyChangedForSubtree();
-    ScrollbarParametersDidChange(false);
+    OnDelegatedScrollOffsetChanged();

[enne (OOO), 2014/10/10 18:10:17]

bikeshed: This isn't really just for "delegated" if you call it here.  Also, it
gets called when either delta or offset changes, so it's not just "Offset"
either.  What about DidScroll?

[boliu, 2014/10/10 18:23:11]

Sounds good. Done.

   }
 }
 
 gfx::Vector2dF LayerImpl::ScrollDelta() const {
   if (scroll_offset_delegate_) {
     return scroll_offset_delegate_->GetTotalScrollOffset().DeltaFrom(
         scroll_offset_);
   }
   return scroll_delta_;
 }
@@ skipping 419 matching lines @@
 }
 
 void LayerImpl::NotifyAnimationFinished(
     base::TimeTicks monotonic_time,
     Animation::TargetProperty target_property) {
   if (target_property == Animation::ScrollOffset)
     layer_tree_impl_->InputScrollAnimationFinished();
 }
 
 }  // namespace cc