[android_webview] Use a fraction to calculate scroll offset.

cc/layers/layer_impl.cc

Index: cc/layers/layer_impl.cc
diff --git a/cc/layers/layer_impl.cc b/cc/layers/layer_impl.cc
index b0c5399d32e3a3fd06c1963eb585e671e52a6ca4..0fdb563fa28d63d820423a4a615abeadd250856d 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -519,13 +519,13 @@ void LayerImpl::PushPropertiesTo(LayerImpl* layer) {
   layer->SetSublayerTransform(sublayer_transform_);
   layer->SetTransform(transform_);
 
+  layer->SetMaxScrollOffset(max_scroll_offset_);

[aelias_OOO_until_Jul13, 2013/09/24 22:03:19]

nit: moving this line for no reason?

[mkosiba (inactive), 2013/09/25 14:23:49]

Done.

+
   layer->SetScrollable(scrollable_);
   layer->SetScrollOffsetAndDelta(
       scroll_offset_, layer->ScrollDelta() - layer->sent_scroll_delta());
   layer->SetSentScrollDelta(gfx::Vector2d());
 
-  layer->SetMaxScrollOffset(max_scroll_offset_);
-
   LayerImpl* scroll_parent = NULL;
   if (scroll_parent_)
     scroll_parent = layer->layer_tree_impl()->LayerById(scroll_parent_->id());
@@ -1001,8 +1001,10 @@ void LayerImpl::SetScrollOffsetDelegate(
   }
   gfx::Vector2dF total_offset = TotalScrollOffset();
   scroll_offset_delegate_ = scroll_offset_delegate;
-  if (scroll_offset_delegate_)
+  if (scroll_offset_delegate_) {
+    scroll_offset_delegate_->SetMaxScrollOffset(max_scroll_offset_);
     scroll_offset_delegate_->SetTotalScrollOffset(total_offset);
+  }
 }
 
 void LayerImpl::SetScrollOffset(gfx::Vector2d scroll_offset) {
@@ -1088,6 +1090,9 @@ void LayerImpl::SetMaxScrollOffset(gfx::Vector2d max_scroll_offset) {
     return;
   max_scroll_offset_ = max_scroll_offset;
 
+  if (scroll_offset_delegate_)
+    scroll_offset_delegate_->SetMaxScrollOffset(max_scroll_offset_);
+
   layer_tree_impl()->set_needs_update_draw_properties();
   UpdateScrollbarPositions();
 }